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Arizona Complex League Mariners

The Mariners (ACL Mariners) are a -level team affiliated with the Seattle Mariners of , serving as an entry point for the organization's newest professional draftees and international signees. Based in , the team competes in the Arizona Complex League (ACL), a short-season developmental circuit that operates from late June to early August, primarily featuring games on the practice fields of complexes. The ACL Mariners play their home games at the , a multi-purpose facility shared with the Seattle Mariners and San Diego Padres during Cactus League . Founded in 1989 as the Arizona League (AZL) Mariners, the franchise initially played in , before relocating to Peoria in 1993, where it has remained a cornerstone of the Mariners' player development pipeline. The team transitioned to the in 2021 as part of Baseball's reorganization, which consolidated rookie leagues and eliminated short-season Class A affiliations, allowing the ACL Mariners to continue providing instructional opportunities in a competitive environment. Over its history, the franchise has achieved notable success, securing four AZL championships in 2000, 2007, 2009, and 2016, while developing early-career talents such as pitchers Shawn Chacón and position players like Wilson Delgado. In recent seasons, the ACL Mariners have maintained a competitive presence in the ACL West division, posting a 31-29 record in 2025 to finish fourth, with a focus on evaluating and refining prospects through high-volume innings and at-bats. The team's roster typically includes a mix of high school draftees, college players, and international s, emphasizing fundamental skills development in a low-pressure setting that bridges and higher levels.

History

Formation and Early Years

The Arizona League was founded in 1988 as a rookie-level circuit to provide initial professional experience for newly signed players, and the Seattle Mariners entered the league that year through a cooperative affiliation with the Red Sox, forming the Red Sox-Mariners team. The co-op squad, managed by Mike Verdi and Myron Pines, struggled in its inaugural season, compiling a 12-47 record and finishing fourth in the four-team league. In 1989, the Mariners transitioned to an exclusive affiliation, establishing the Arizona Mariners as their dedicated team in . The initial roster was composed primarily of undrafted free agents and signees, reflecting the league's role as an for players beginning their professional careers. Under manager Dave Myers, the team posted a 26-26 record, tying for third place in a six-team division. The 1990 season brought the franchise's first winning record at 32-21, securing second place and highlighting early progress in player acclimation. Managerial turnover marked the decade, with Myron Pines taking over in 1991 (33-27 record, third place), followed by Carlos Lezcano in 1992 (32-24, tied for second). In 1993, the team relocated its home base from Tempe to the in . Marty Martinez from 1993 to 1994 (combined 39-71, last place both years), Tom LeVasseur in 1995-1996 (53-59 overall, including a 29-27 third-place finish in 1996), Darrin Garner in 1997-1998 (61-50 overall, second place both years), and Gary Thurman in 1999 (32-24, second place). Throughout the pre-2000 era, the Arizona Mariners functioned as a foundational component of the organization's player development pipeline, introducing recent MLB Draft selections—particularly high school and signees—alongside undrafted free agents and international amateurs to the rigors of in a controlled environment. This setup allowed for rapid assessment and initial skill refinement, with draftees from classes like integrating directly into the system to build toward higher levels.

Notable Milestones and League Evolution

The Arizona Complex League Mariners have secured four league championships since 2000, marking significant achievements in their developmental history. In 2000, the team clinched the title under manager Omer Munoz, finishing with a 39-16 record and defeating the AZL Rockies 1–0 in the finals. The 2007 championship came after a strong 37-19 season led by manager Jose Moreno, culminating in a playoff victory over the Arizona League Giants. Two years later, in 2009, Andy Bottin guided the Mariners to a 33-22 regular season and another title, again besting the Giants in the championship series. The most recent triumph occurred in 2016, when the team, managed by Zac Livingston, swept the Arizona League Angels in the finals, highlighted by outfielder Ryan Uhl's go-ahead two-run homer in Game 2 of the series. The league and team faced major disruptions in 2020 when canceled its entire season, including the Arizona League, due to the , marking the first full cancellation since the league's inception. This hiatus affected player across all affiliates, with no games played from to September as originally scheduled. The season resumed in 2021 following MLB's comprehensive minor league restructuring, which renamed the Arizona League to the to better reflect its role as a complex-based circuit integrated into the new framework. This change aligned the ACL with similar Florida operations, emphasizing year-round training and evaluation at team facilities while maintaining a similar playoff structure of divisional half-season winners. Since the early 2000s, the Mariners' affiliate has evolved into a critical hub for player development, serving as a primary transition point for prospects from the (DSL). The team operates two DSL squads, which feed directly into the for advanced instruction in , allowing signees to adapt to U.S.-based facilities and competition sooner after their initial summer exposure. This has grown in importance post-restructuring, with shared philosophies and cross-league assignments enhancing progression for Latin American talent, such as position players refining defensive metrics and pitchers building velocity in controlled environments.

Facilities and Operations

Home Venue and Training

The Arizona Complex League Mariners primarily play their home games at the in , a 145-acre facility shared with the San Diego Padres organization. Opened in 1994 as the first two-team complex in history, it serves as the year-round home for player development programs, including the ACL Mariners since that year. The main stadium, Peoria Stadium, has a seating capacity of 12,518 and features field dimensions of 340 feet to the left and right field corners, 385 feet to the alleys, and 410 feet to center field. The complex includes 13 full-size fields—seven of which are lighted—along with four half fields, supporting extensive and schedules tailored to rookie-level development. Training resources encompass eight covered major league-sized batting cages and 12 hitting tunnels, 30 practice mounds, and dedicated clubhouses for the Mariners spanning 56,368 square feet, equipped with over 400 personnel lockers, dining areas, weight training rooms, and facilities for medical rehabilitation. These amenities are designed to foster foundational skills in young prospects, with areas particularly suited for injury recovery in the complex league environment. Significant upgrades have enhanced the venue's functionality over time, including a renovation of the clubhouses to LEED Gold certification standards, adding modern training spaces, and a 2015 expansion that incorporated over 400 new seats, ADA-compliant improvements, and a 2,400-square-foot team store. In 2025, the Mariners completed refurbishments to their bullpens and batting cages, improving durability and technology for daily workouts. Beyond regular games, the complex hosts contests, youth tournaments, and community events, broadening its role in regional baseball development. Operational logistics at the facility revolve around coordinating usage between the shared Mariners and Padres programs, with the ACL Mariners' summer schedule (typically June to August) following the MLB spring training period (February to March) to optimize field availability. This year-round player development setup ensures seamless transitions for rookies, minimizing disruptions while accommodating both organizations' needs.

Coaching Staff and Organizational Role

The Arizona Complex League (ACL) Mariners coaching staff for the 2025 season is led by manager Rico Reyes in his first year in the role, having previously served as the team's bench and outfield/base running coach for two seasons. Reyes, a University of North Texas alumnus, brings experience from his time as an assistant coach at Odessa College and in independent professional baseball. Bench coach Chase Wullenweber joins the organization for the first time, after working as an assistant coach at Murray State College in Oklahoma; he played collegiately at Georgia Southern University and Georgia State University. Hitting coach Chase Miller returns for his second season in the position and with the Mariners, following prior work at Ascent Athlete, a performance training facility. Pitching coach Bryan Pall is in his third year with the organization and second in this role, having coached the Dominican Summer League Mariners' pitchers the previous season; Pall was a 2017 draft pick of the Mariners out of the University of Michigan and pitched in their minor league system until 2022. Sergio Plasencia serves as the return-to-play coach, focusing on player rehabilitation and development. As the lowest level in the Seattle Mariners' affiliate structure, the Mariners serve as the primary entry point for recent picks and signees, emphasizing foundational skills , physical , and initial acclimation. The coaching staff operates under the Mariners' player development umbrella, implementing standardized instructional philosophies from the organization to build consistency across levels. This rookie-level placement allows for intensive evaluation of raw talent, with the functioning as a developmental hub in the summer heat, distinct from the year-round operations. Historical managerial turnover in the Mariners has been frequent, reflecting the transient nature of rookie ball coaching, but with occasional stability providing continuity for young players. For instance, Luis Caballero managed the team for two consecutive seasons from 2023 to 2024, compiling a 59-57 record and overseeing the progression of several prospects to higher affiliates. Earlier, Austin held the position in 2021 amid the league's pandemic-shortened schedule. Such tenures, though brief compared to upper minors, have enabled coaches to influence early player habits, with Caballero's emphasis on defensive fundamentals credited for smoothing transitions for draftees to Modesto. The ACL coaching staff plays a pivotal role in the Mariners' scouting and evaluation process, monitoring daily performance metrics to inform promotions within the system. Strong showings in fundamentals—such as plate discipline, fielding, and velocity control—directly factor into decisions for advancement to levels like , where players face more advanced competition. This evaluative function integrates with the organization's broader analytics-driven approach, providing data to scouts and front-office personnel for long-term roster planning.

Performance and Records

Season-by-Season Results

The Arizona Complex League Mariners, previously operating as the Arizona League Mariners until the league's rebranding in , have maintained a rookie-level affiliate presence since their in 1989. The 2020 season was cancelled due to the , resulting in no . The following table summarizes the team's annual performance, including wins, losses, , divisional or finish, and manager where documented.
YearWinsLossesWin %FinishManager
19892828.5003rd ( League)Dave Myers
19903221.6042nd ( League)Dave Myers
19913327.5503rd ( League)Myron Pines
19923224.5713rd ( League)Carlos Lezcano
19931836.3338th ( League)Marty Martinez
19942135.3758th ( League)Marty Martinez
19952432.4294th ( League)Tom LeVasseur
19962927.5183rd ( League)Tom LeVasseur
19973026.5362nd ( League)Darrin Garner
19983124.5642nd ( League)Darrin Garner
19993224.5712nd ( League)Gary Thurman
20003916.7091st ( League)Omer Munoz
20013422.6072nd ( League)Omer Munoz
20022729.4825th ( League)Darrin Garner
20033025.5452nd ( League)Scott Steinmann
20043125.5544th ( League)Scott Steinmann
20052729.4825th ( League)Dana Williams
20062530.4555th ( League)Dana Williams
20073719.6611st ( League)Jose Moreno
20082135.3758th ( League)Andy Bottin
20093322.6001st ( League)Andy Bottin
20102036.3573rd ( League)Jesus Azuaje
20112531.4462nd ( League)Jesus Azuaje
20123125.5542nd ( League)Mike Kinkade
20132232.4073rd ( League)Darrin Garner
20143122.5851st ( League)Darrin Garner
20153125.5542nd ( League)Darrin Garner
20163125.5542nd ( League)Zac Livingston
20173124.5641st ( League)Zac Livingston
20181638.2966th ( League)Zac Livingston
20192234.3937th ( League)Zac Livingston
202000-Season cancelled ()N/A
20213918.6841st (ACL West)Austin Knight
20222629.4734th (ACL West)Luis Caballero
20233125.5542nd (ACL West)Luis Caballero
20242832.4672nd (ACL West)Luis Caballero
20253129.5174th (ACL West)Rico Reyes

Championships and Postseason Achievements

The Arizona Complex League Mariners have secured four league championships in their history, all achieved through postseason play in the single-game or best-of-three finals format typical of the league during those eras. These titles came in 2000, 2007, 2009, and 2016, highlighting periods of strong collective performance in a highly competitive rookie-level . Beyond these, the team has made eight total postseason appearances since 1989, often qualifying via strong regular-season finishes or wild-card berths in the league's divisional structure. In 2000, the Mariners clinched their first title with a 1-0 victory over the AZL Rockies in the single-game championship, capping a dominant 39-16 regular season that placed them first overall. Managed by Omer Muñoz, the team relied on timely hitting and solid relief pitching to secure the win at . No formal was named, but starter Clint Nageotte stood out during the regular season with a 4-1 record and 2.16 ERA, contributing to the postseason push. The 2007 championship saw the Mariners defeat the AZL Giants 8-5 in the decisive one-game final, under manager José Moreno, following a 37-19 regular season good for first place. Jake Wild delivered a standout performance, striking out 14 batters in the championship game to earn recognition as the key contributor, while the offense exploded for eight runs. This victory marked the team's second title and underscored their ability to thrive in high-pressure situations. In 2009, finishing first in the West Division in the at 33-22, the Mariners advanced through the expanded and edged the AZL Giants in the one-game final on at Scottsdale . Managed by Andy Bottin, the team benefited from balanced contributions across the roster, with no single highlighted, but the win solidified their status as a postseason contender. (Note: Game logs confirm the score, aligning with official imagery records.) The 2016 title was the most recent, with the Mariners sweeping the best-of-three finals 2-0 over the AZL Angels, including a 3-1 victory in Game 2 on September 3. Under manager Zac Livingston, who guided a 31-25 regular-season team to the crown, Ryan Uhl provided the decisive blow with a go-ahead two-run homer in the fourth inning of the clincher. Pitchers and Carlos Hernández combined for effective starts, while reliever David Ellingson notched the save with a perfect ninth. Outside of championships, the Mariners reached the postseason in 2001 (34-22 regular season, lost finals to the AZL Athletics), 2014 (31-22, lost in second round to the AZL Cubs), 2015 (31-25, lost finals to the AZL D-backs), and 2017 (31-24, lost first round to the AZL Giants). These appearances demonstrate consistent divisional contention, particularly in the , though they fell short of further titles. No additional postseason berths occurred from 2018 to 2025, with the 2020 season canceled due to the .
YearBatting AverageERANotes on Performance
2000.3164.10Highest offensive output among title years; strong regular-season finish propelled playoff run.
2007.2673.39Lowest ERA, reflecting pitching staff's control in championship game.
2009.2683.78Balanced attack in low-scoring final; wild-card qualification key to advancement.
2016.2683.66Sweep highlighted timely power hitting and bullpen reliability.
Across these championship seasons, the Mariners exhibited patterns of pitching dominance, with ERAs consistently below the league average (typically around 4.50 in the ), enabling success in tight, low-scoring playoff games. Offensive efficiency, rather than raw power, proved crucial, as evidenced by batting averages hovering near .270 in three of four title years, allowing the team to capitalize on opportunities against evenly matched opponents.

Players and Personnel

Current Roster

The Arizona Complex League Mariners' 2025 roster, as of November 14, 2025, totals 36 active players with no individuals on the or with specified expected return dates. The composition reflects a blend of Seattle Mariners' recent MLB Draft selections—particularly from the 2025 class—and international signings, with mid-season transactions limited to routine player assignments and no major trades or releases reported through the postseason.

Pitchers

The pitching staff features 24 players, emphasizing young arms with a focus on development for the Mariners' farm system.
NameAgeB/TAcquisition Method
Kade Anderson21L/L2025 MLB Draft, 1st round (3rd overall)
Gregori Arrieche23R/RInternational
Juan Cazarez20R/RInternational
Anderson Guevara20R/RInternational
Thomas Higgins Jr.22R/RUndrafted
Griffin Hugus21L/R2025 MLB Draft, 3rd round (91st overall)
Juan Jimenez18R/RInternational
Anthony Karoly21R/R2023 MLB Draft, 18th round
Po-Chun Lin19L/RInternational
Danny Macchiarola21L/RUndrafted
Kendal Meza19R/RInternational
Ruddy Navarro19R/RInternational
Francisco Pazos19R/RInternational
Roberto Perez21R/RInternational
Mason Peters21L/L2023 MLB Draft, undrafted
Cole Phillips22R/R2021 MLB Draft, 12th round
Juan Pinto21L/LInternational
Ruben Ramirez20R/RInternational
Dusty Revis23R/R2025 MLB Draft, 11th round
Wuilliams Rodriguez21R/RInternational
Jose Romero21R/RInternational
Jackson Steensma21S/R2023 MLB Draft, 16th round
Eduardo Uscanga18R/RInternational
Dylan Wilson19R/RInternational
Ages calculated from date of birth as of November 14, 2025.

Catchers

The catching group includes 5 players, providing depth for instructional and game experience.
NameAgeB/TAcquisition Method
Sebastian De Andrade19R/RInternational
Carlos Gonzalez21R/RInternational
Luke Heyman22R/R2025 MLB Draft, 14th round (422nd overall)
Grant Jay22R/R2025 MLB Draft, 12th round
Eduardo Ponce19R/RInternational

Infielders

Four infielders round out the position player core, focusing on versatile defenders and hitters.
NameAgeB/TAcquisition Method
Martin Gonzalez21R/RInternational
Bryant Mendez22R/RInternational
Estevan Moreno22R/RUndrafted
Brady O'Brien23R/RUndrafted (2025)

Outfielders

The outfield consists of 3 players, emphasizing speed and power potential.
NameAgeB/TAcquisition Method
Kelvin Alcantara20L/LInternational free agent
Brayden Corn22R/RUndrafted free agent
Konni Durschlag23R/R2022 MLB Draft, 18th round
The coaching staff supports player development with the following roles: Luis Matias and Rico Reyes (managers), Chase Wullenweber (bench coach), Chase Miller (hitting coach), Bryan Pall (pitching coach), and Sergio Plasencia (coach).

Notable Alumni

The Arizona Complex League Mariners (formerly the Arizona League Mariners) have served as an important developmental hub for numerous players who advanced through the Seattle Mariners' system to , often beginning their professional careers or making key adjustments at the level. Many spent limited time in the due to rapid promotions, but their early exposure in contributed to skill refinement before higher assignments. Position players and pitchers alike have emerged from the program, with several achieving status or long-term MLB roles.

Position Players

Prominent position player alumni include Alex Liddi, who signed as an international free agent in 2005 and debuted professionally with the AZL Mariners in 2006, where he batted .313 with 57 hits, 5 home runs, and 34 in 46 games, finishing fifth in the league batting title race. Liddi progressed through the Mariners' affiliates and made his MLB debut in 2011, appearing in 101 games over three seasons (2011–2013) primarily as a and , hitting .208 with 6 home runs before continuing his career in other organizations and international leagues. Kyle Seager, selected in the third round of the 2009 MLB Draft out of the , joined the AZL Mariners late in his debut season on July 15, 2009, playing one game and going 0-for-3 at the plate. Despite the brief stint, Seager quickly advanced, reaching the majors by 2011 and enjoying a distinguished 11-year career exclusively with the Mariners through 2021, where he earned three selections (2014, 2016, 2018), hit 35 home runs in 2021, and accumulated 1,401 hits with a .253 . More recent graduates include José Caballero, originally drafted by the Arizona Diamondbacks in the seventh round of the 2017 MLB Draft from Chipola College and acquired by the Mariners in a December 2018 trade for cash considerations. Caballero played sparingly but effectively in the AZL/ACL Mariners across three seasons: .455 batting average in 3 games (2019), .280 with 2 home runs in 8 games (2021), and .600 in 2 games (2022). He debuted in MLB with the Mariners in 2023, appearing in 104 games with a .221 average and 26 stolen bases, before being traded to the Tampa Bay Rays; in 2024, he led the American League with 44 stolen bases in 139 games. In 2025, Caballero led MLB in stolen bases before being traded to the New York Yankees on August 1. Jonatan Clase, signed as an international free agent from the in 2018 for $35,000, spent part of his 2021 season with the ACL Mariners, batting .245 with 2 home runs, 10 , and 16 stolen bases in 14 games while showcasing elite speed. Clase advanced rapidly through the system, debuting in MLB with the Mariners on April 15, 2024 (19 games overall in 2024, .195 average, 3 stolen bases) before a midseason trade to the Blue Jays, where he played 7 games that year; he continued with the Blue Jays in 2025, appearing in 34 games.

Pitchers

Among pitchers, Eric O'Flaherty stands out as a sixth-round pick in the 2003 MLB Draft out of Walla Walla High School (), posting a strong 3-0 record with a 1.95 ERA, 20 strikeouts, and 7 walks in 13 appearances (27.2 innings) for the AZL Mariners that year. O'Flaherty debuted in MLB with the Mariners in 2005 and enjoyed a 12-year career (2005–2016) across multiple teams, primarily as a left-handed reliever, compiling a 3.70 ERA in 408 games with 20 saves. Julio Mateo, signed as an international free agent from the Dominican Republic in 1996, excelled in 1997 with the AZL Mariners, going 3-1 with a 3.30 ERA and 54 strikeouts in 60 innings over 13 appearances. Mateo reached the majors with the Mariners in 2002, serving as a reliable middle reliever through 2007 (3.23 ERA in 197 games) before returning to international baseball. These alumni exemplify the ACL Mariners' role in nurturing talent, with post-2015 graduates like Caballero and Clase highlighting the program's continued pipeline to the majors as of 2025.

Rehabilitation Assignments

Program Overview

The () Mariners serve as a key venue for () player rehabilitation assignments, particularly for Seattle Mariners players recovering from injuries. These assignments allow injured players on the 10-day, 15-day, or 60-day to participate in games and practices to regain game readiness without impacting major league rosters. In the context of rookie-level leagues like the , rehab stints emphasize a low-pressure environment suitable for gradual reintegration, where players can face live competition while adhering to individualized recovery plans determined by the organization's player development staff. MLB rules under Rule 6(g) govern these assignments, permitting players to rehabilitate with affiliates such as the Mariners, provided they obtain player consent and approval from the Commissioner's Office. For position players, the maximum duration is 20 days, while pitchers are limited to 30 days, with possible extensions for specific surgeries like UCL reconstruction up to an additional 30 days with approval. In the context, these stints are tailored to the league's rookie-level structure, focusing on controlled workloads; Mariners-specific guidelines, integrated with medical staff at the , include customized limits and at-bat targets to prevent re-injury, though exact thresholds vary by individual case and are set by development personnel. Rehab players do not count against the host team's active roster limits, enabling up to three concurrent assignments per team at lower levels like or below. The Mariners have utilized the for rehabilitation since the mid-1990s, coinciding with the opening of the in , which has served as the organization's for player rehab programs. This historical integration involves close coordination between athletic trainers, strength coaches, and medical staff to monitor progress, with frequency depending on injury volume—typically several players per season undergo ACL stints as part of broader recovery protocols. The program's advantages include a controlled setting with access to specialized facilities like hydrotherapy pools and pitching mounds, fostering safe progression in a familiar environment proximate to the Mariners' site, which minimizes travel and supports seamless transitions back to action.

Notable Stints and Impact

One prominent example of a rehabilitation assignment in the () Mariners occurred in May 2025, when right-handed pitcher began his recovery from surgery performed the previous year. Kowar made his ACL debut on May 4 against the ACL Royals, pitching one inning in which he allowed two runs (one earned) on two hits while striking out one batter. Over his subsequent rehab appearances split between the ACL and Triple-A Tacoma, Kowar logged eight outings (two starts) with a 2.57 ERA across 10.1 innings, paving the way for his activation from the 60-day on May 28 and return to the bullpen. However, Kowar later encountered a shoulder issue in September 2025, leading to another placement and highlighting the challenges of post-surgery recovery timelines, which extended his time away from the majors into late 2025. Similarly, veteran reliever joined Kowar in the for rehab work in early May 2025, following his own surgery in March 2024. In his initial outing on May 4, Gott pitched a scoreless , surrendering one hit with no walks and one . Despite this promising start, Gott's overall rehab performance across 6.1 innings yielded a 9.95 , contributing to the Mariners' decision to release him on June 3, 2025, before he could return to the active roster. This case illustrates a notable failure in the rehab process, as Gott's velocity and command did not fully rebound, ultimately ending his tenure with the organization after a brief 2023 stint. Post-release, Gott was re-signed by the Mariners to a minor league contract on June 8, 2025, but did not appear in MLB games in 2025. Left-handed reliever underwent a successful rehab in July 2024 after a left strain sidelined him since late May. Speier's second rehab appearance on July 15 featured one scoreless inning with one hit, no walks, and two groundouts, building on a prior scoreless frame earlier that week. He completed his assignment without setbacks and was reinstated to the roster on July 19, where he contributed 12.1 innings in relief over the remainder of the 2024 season with a 3.65 . Speier's efficient return underscored the 's role in facilitating quick recoveries for shoulder injuries, allowing him to bolster the Mariners' during a playoff push. Long-term, this stint helped stabilize Speier's career trajectory, as he remained a key lefty specialist into 2025. In September 2021, right-hander Diego Castillo rehabbed a right inflammation with the ACL Mariners, appearing in one game on September 2. Castillo delivered a perfect inning, striking out two batters without allowing a hit or walk, which expedited his activation from the 10-day on September 4. This brief but effective outing enabled Castillo to return to the Mariners' , where he pitched 5.2 scoreless innings over four appearances to close the season. The quick turnaround positively influenced Castillo's career, as he logged 58.1 innings with a 2.93 in 2022 before further issues arose in subsequent years, demonstrating the ACL's utility for short, targeted rehab for inflammation-related ailments. Outfielder Kyle Lewis utilized an 11-game rehab stint with the Arizona League (AZL) Mariners in June 2017 to recover from lingering effects of a 2016 ACL tear in his right knee. Lewis posted a .260 average during this period, regaining timing and defensive mobility at center field before rejoining High-A Modesto on July 20. His overall 2017 performance across levels reached .257/.332/.434 with seven home runs in 49 games, culminating in a strong Arizona Fall League showing (.315/.394/.553 in 24 games) that affirmed his top-prospect status. Lewis debuted in the majors with the Mariners in 2019, earning AL Rookie of the Year honors with a .257 average and 21 home runs, though recurring knee and other injuries limited him to just 111 games over the next four seasons before his release in 2023. The 2017 AZL rehab proved pivotal in bridging his minor league development to MLB success. Prospect shortstop Colt Emerson began his 2024 rehab assignment in the Mariners on June 27 following a fractured foot sustained in May. In his debut, Emerson went 1-for-4 with a run scored, playing five innings at without error, including a hustle double from first to third on a single. Across two rehab games (one in , one in Modesto), he batted 2-for-7 before activation on June 30. Emerson's seamless return contributed to a breakout season (.290/.396/.463 with 10 home runs in 82 games), solidifying his status as the Mariners' No. 1 prospect entering 2025. This early rehab success minimized lost development time, positioning him for a potential Double-A promotion in 2025 and accelerating his path to the majors. These cases reflect a mix of outcomes in ACL rehab assignments from 2017 to 2025, with successes like Speier and Castillo enabling prompt returns and career extensions, while setbacks for Gott and Kowar underscore recovery variability. Overall, such stints have supported player development by providing low-pressure environments for building or at-bats, often leading to sustained contributions at higher levels for those who progress fully.

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