Aidan Miller Joins Phillies Fall League Contingent

After making his 2026 season debut on a rehab assignment with the Clearwater Threshers in September, Phillies top infield prospect Aidan Miller was selected to join a group of now ten Phillies prospects in the upcoming Arizona Fall League season that begins on Saturday, October Third. He will join the Surprise Saguaros with nine of the ten Phillies players detailed in last week's hitters preview article.

Aidan Miller - INF 2023-24

A top 100 prospect (per MLB.com) since the Phillies drafted him in 2023, Miller was selected to participate in last year's Arizona Fall League before a back injury forced him to leave the Saguaros before the fall season started in 2025. That same back injury held Miller out of baseball action until September of his fourth professional season, when he doubled in a rehab stint in Clearwater with the Threshers. Miller went a combined 7-24 in seven games with the Reading Fightin Phils, including three RBIs in four postseason games that helped Reading to their first Eastern League title in over thirty years. Miller started all four playoff games at third base for the Fightin Phils, his first action at the hot corner since turning pro in 2023.

The move to third base has been long-anticipated for Miller, a natural who has not played third base in a competitive game since high school. Though he has certainly proved his fielding skills are developed enough to play shortstop at an elite level, Miller's path to shortstop is blocked by Trea Turner, who has seven years left in a deal worth $300 million. All 215 times Miller started in the field during the regular season were at shortstop, where he has played over 1800 innings throughout four years in the Phillies minor league system. However, Bryan Rincon's emergence at the same position in Reading opened up the possibility for Miller to try third base for the first time as a pro, and he committed just one error in 36.0 innings at the hot corner during Reading's championship run. Miller is expected to get more time at third base with the Saguaros, as well as a chance to catch up on a season nearly lost completely to injury.

Here are some of the pitchers who will join Aidan Miller on the Surprise Saguaros when the 2026 Arizona Fall League season starts on October 3:

Keegan Batka - RHP 2025-26

Of the ten Phillies prospects participating in the 2026 Arizona Fall League, Keegan Batka is the only one who began last season on Clearwater's opening-day roster. The non-drafted free agent pitcher signed with the Phillies as a starter in 2025, but has pitched exclusively out of the bullpen since debuting with the Threshers in August 2025. He was lights out for Clearwater in the first half of the season, tossing 12.1 scoreless innings over ten relief appearances with the Threshers before earning a call-up to Jersey Shore in May. He finished the season in Double-A with the Fightin Phils, joining Gage Wood and Cody Bowker as the only three Threshers who jumped two levels to Double-A in 2026.

The Arizona Fall League has long been a place for top prospects and unheralded alike to showcase their skills and prove to their respective teams that they have what it takes to make it to the major leagues. As one of the few non-drafted free agents invited to participate in this prestigious league, Batka has a chance to make some serious waves against some of the top talent in the minor leagues. Between Clearwater, Jersey Shore, and Reading this season, Batka demonstrated the ability to work multiple innings and just be a one-inning guy late in games. In just one month with the Threshers, Batka managed five saves in five opportunities, finishing in a tie for seventh in the Florida State League. He also became the first Threshers reliever to get called up after ten scoreless outings since Orion Kerkering in 2023. Unlike Kerkering, Batka didn't achieve the rare distinction of getting a big-league call-up in his first full season as a pro, but a good fall in Surprise could make Batka a rapid riser in 2027.

Ryan Dromboski - RHP 2025

One of three Phillies players signed as a non-drafted free agent who will be in Arizona this fall, Ryan Dromboski has emerged as a dependable starter in the Phillies' farm system. He debuted with the Threshers in 2025 after signing out of Penn in August of 2024. He split time between the bullpen and starting rotation for the Threshers in his first pro season, not getting a start until his sixth appearance at the end of April 2025, and started eight more times in eleven more outings before earning a late-season call-up to Jersey Shore. He began 2026 in High-A before midseason injuries limited his time in Reading. He got the ball for the clinching game of the Eastern League Championship Series, but pitched a total of 9.0 innings over three starts for the Fightin Phils.

Dromboski has shown the ability to handle a starter's workload, pitching over 80 innings in each of his first two seasons in the minor leagues. Now is his time to take the next step in his career evolution and improve upon a solid first two years. The right-hander has compiled a 12-16 record and a 4.13 ERA over two minor league seasons and three levels, serving as a key piece of the Threshers' second-half title in 2025 and the Fightin Phils' championship run this past month. In his first fall season of baseball, Dromboski looks to join the company of Andrew Painter as he looks to rise from the Fall League to the high minors to Philadelphia.

Estibenzon Jiménez - RHP 2022-23

After switching from the starting rotation to the back end of the bullpen in 2026, Estibenzon Jiménez has emerged as one of the most fascinating Phillies prospects heading to the desert for fall baseball. Jiménez has split his time between the starting rotation and the bullpen almost right down the middle since signing out of Venezuela in 2019. He had been trending towards the starting rotation since joining Clearwater at the end of the 2022 season, but in all 35 appearances, Jiménez entered out of the bullpen. He allowed two runs in 13.2 rehab innings across three levels in the FCL and A-Ball before transforming into one of the most effective relievers in the Eastern League. Jiménez finished 2025 with a 3-4 record and a 4.63 ERA in 13 starts for Reading. In 28 relief appearances, he compiled a 5-0 record and made seven saves in as many appearances, factoring into a winning decision in nearly half of his games for the Fightin Phils. He also pitched in three of four playoff games out of the bullpen, recording the save in game one of the championship series on the road and sealing the clincher at home in game two.

Jiménez has evolved from an innings-eating, groundout-getting starter to a clutch reliever with overpowering stuff. He is the latest in a line of former Phillies minor league starters who have transformed into full-time relievers, with his former Threshers teammate Alex McFarlane a prime example of a pitcher who achieved success despite a switch from the starting rotation. McFarlane made the switch to the bullpen in High-A last year and will end the 2026 season on the Phillies' playoff roster. With his impressive pitching in high-leverage situations with the Fightin Phils, Jiménez had his breakout as a reliever in 2026. Another season like he just had, and he could be challenging McFarlane for a spot in the Phillies' bullpen.

Jose Peña Jr. - RHP 2024-25

A sixth-rounder out of Tampa Prep in 2021, things really started to click for Jose Peña Jr. in his second season with the Threshers in 2025. Peña made Clearwater's opening day roster in 2024 and 2025, going from one of the first pitchers out of the bullpen to Clearwater's trusted late-inning arm in his second season. After going 4-3 with an ERA over 5.00 in 2024, Peña returned with an ERA under 1.00 and five saves in 20 relief appearances with the Threshers last season, with a 4-1 record. Since joining the Jersey Shore BlueClaws in June of 2025, Peña has thrown over 40.0 High-A innings to the tune of a 2.70 ERA. However, Peña has not pitched since June 21, when he retired both batters he faced in a scoreless 0.2 innings in Shoretown before succumbing to a season-ending injury. It finished Peña's best month of the 2026 season, where he allowed just one run and struck out eleven batters over 6.1 innings and six relief appearances in his final month of the year. Peña won a championship in Puerto Rico with the Cangrejeros of Santurce last offseason and now looks to work his way back after missing the final two months of the 2026 season.

This year's Arizona Fall League is a chance for Peña Jr. to show that his stuff is suited for the high minors. With a fastball that sits in the high 90 mph range, that should not be a problem for the 23-year-old righty. He is one of four players still with the organization from the Phillies' 2021 draft class, but he has improved every year in the minors since. With the defending champion Saguaros, Peña will have to fight for a spot in the later portion of the bullpen, even with some of his fellow pitchers in the Phillies organization. He is also one of the longest-tenured members of the entire Phillies farm system, so his leadership abilities will be on full display as well. This will be Peña's first taste of pro ball above the High-A level outside of 1.0 inning in Spring Training during this past Grapefruit League season. He has plenty to prove and a lot to be excited about in his first year of Arizona Fall League baseball.

Kevin Warunek - LHP 2025-26

Injuries, unfortunately, were a common theme among the Phillies' selection decisions for their Arizona Fall League roster. Few players in their system felt that pain more than Kevin Warunek, a left-handed reliever drafted in the eighteenth round out of Longwood in 2024. Opponents hit just .224 against him in his debut 2025 season, but Warunek missed most of each half of the 2026 season and had rehab stints in Clearwater in both May and August of 2026. In between rehab outings in Clearwater, Warunek did not allow an earned run in his lone Double-A inning, with just two earned runs allowed in 10.2 innings in High-A Jersey Shore.

Warunek broke out with the Threshers in 2025, posting a 4/1 strikeout-to-walk ratio with a 2.91 ERA in 34.0 innings before earning a midsummer call-up to the Jersey Shore BlueClaws. In 43 relief appearances in the last two seasons, Warunek has compiled a 5-0 record with two saves. He can seemingly pitch anywhere out of the bullpen, and could get a better idea of his role in the future depending on how he is utilized by the Saguaros in the next two months. It's been a small sample size for the lefty, but Warunek has shown promise as a late reliever throughout his first two years as a pro. A solid month in Arizona could help him get ready to work in the high minors, as Warunek hopes to return to Double-A to begin the 2027 season.

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