Ten Arizona Fall League Sleepers To Watch In 2023


Image credit: Reds RHP Zach Maxwell could make a name for himself at the Arizona Fall League. (Brad Krause/Four Seam Images)

The 30th season of the Arizona Fall League begins on Oct. 2. The initial rosters, which were released on Sept. 22, featured nine of Baseball America’s Top 100 prospects, including White Sox shortstop Colson Montgomery, who ranks No. 14. 

Beyond those nine, however, there are plenty more prospects who could open eyes and jump up their organization’s rankings. 

Oakland righthander Mason Miller dominated the Arizona Fall League in 2022 and made his big league debut this April. Johan Rojas turned in six weeks of highlight-reel plays in Arizona. Now he patrols center field in Philadelphia. 

Bryan Woo and Emmet Sheehan were two of the league’s most talented pitchers. They both have a chance to take the national stage this October. 

Here are 10 players who could follow that script this fall in the 2023 Arizona Fall League. 

Zach Maxwell, RHP, Reds
At 6-foot-6 and 275 pounds, Maxwell is a physical, intimidating presence on the mound. That he throws a 98 mph fastball with outstanding life is almost a bonus. Maxwell’s four-seamer is one of the best pitches in the minor leagues, period, with more than 20 inches of induced vertical break and an in-zone miss rate of nearly 34%. He backs it up with a filthy slider in the high 80s that serves as a fantastic knockout pitch that racked up a 44% miss rate. Simply put, Maxwell can tear hitters apart. 

Kala’i Rosario, OF, Twins
The Midwest League’s MVP was one of the most patient hitters on the circuit this year. He worked deep counts all year long, leading to the fifth-most walks and third-most strikeouts in the MWL. He also made plenty of impact, leading to a league-best 21 home runs. His 90th percentile exit velocity of 107.1 mph put him in the same neighborhood as higher-profile prospects like James Wood, Noelvi Marte and Tyler Soderstrom. 

Ronan Kopp, LHP, Dodgers
Kopp is a tall southpaw whom the Dodgers took out of South Mountain (Ariz.) JC in the 12th round of the 2021 draft. He limited contact and got plenty of strikeouts this past season, but he also had trouble throwing strikes and walked more than six hitters per nine innings. He works primarily with two pitches: a mid-90s four-seam fastball with more than 20 inches of induced vertical break and a mid-80s slider with big-time spin and a whiff rate of nearly 60%. He’ll also mix in the occasional cutter, changeup and curveball. If he can throw consistent, quality strikes, he has a chance to be one of the next members of the Dodgers’ pitching factory. 

 Zach Dezenzo, 3B, Astros
Dezenzo was one of the biggest breakout prospects in Houston’s system this season. The 2022 12th-round pick out of Ohio State crushed the South Atlantic League and then hit well after moving to Double-A. Dezenzo hits the ball quite hard—his 90th percentile exit velocity finished just a shade under 108 mph—and did an excellent job of finding the barrel at both stops. He could follow the same path as Will Wagner blazed in 2022, when the Astros prospect torched the competition in the AFL.

Nathan Martorella, 1B, Padres
Top Padres prospects usually fit the mold of the tooled-up, high-risk, high-reward player with immense ceilings but plenty of room to fail. Martorella is the opposite. He’s a gifted hitter who produced on-base ability and power spread across two levels. The fifth-rounder out of California from 2022 did a fantastic job this season of staying within the strike zone and making contact with strikes. The result was 49 extra-base hits—30 doubles and 19 home runs—and nearly as many walks (82) and strikeouts (101) and a strikeout of just 17%.

Jack Brannigan, SS, Pirates
Brannigan was Pittsburgh’s third-rounder from 2022 out of Notre Dame. More than that, he was one of the best performers in the Pirates’ system this season. Between two Class A levels, he hit 14 doubles, 19 home runs and stole 24 bases in 27 tries. Brannigan’s strikeout rate of roughly 30% is a red flag, but he hit the ball fairly hard and did a good job finding the barrel. If he can cut down on his whiffs, he might open some eyes in the AFL.

Justice Bigbie, OF, Tigers
Bigbie was one of Detroit’s more prominent pop-up prospects this season. The 19th-rounder from Western Carolina started his season in High-A and finished in Triple-A, homering 19 times along the way. Bigbie is nearly 25 years old and was more advanced than the competition at both High-A and Double-A. Still, he struck out just 77 times all year and showed plenty of impact, including an average exit velocity of 92 mph.

Christian McGowan, RHP, Phillies
McGowan returned from Tommy John surgery in July and showed impressive stuff. He was Philadelphia’s seventh-round pick in 2021 out of Eastern Oklahoma JC. Upon his return, McGowan showed a mid-90s two-seamer, a mid-80s slider and a high-80s changeup. More specifically, he works with two sliders—a gyro version for early-count strikes and a sweeper for late chases. As would be expected of someone with his repertoire, McGowan gets grounders by the bushel.

Tekoah Roby, RHP, Cardinals
Roby was one half of the return St. Louis received from Texas in exchange for lefty Jordan Montgomery. He was also part of Texas’ extremely talented 2020 draft class—which also includes big leaguer Evan Carter and breakout prospect Thomas Saggese—but has dealt with injuries this season that limited him to just 58.1 innings. Roby works with a full four-pitch complement but his bread-and-butter pitches are a mid-90s four-seam fastball and a high-70s, high-spin curveball. 

Brainer Bonaci, SS, Red Sox
In a season limited by injuries, Bonaci was impressive. The 21-year-old reached Double-A and clubbed 18 doubles and 11 home runs in 79 games. He was one of three players his age or younger to reach those marks in that amount of playing time. Despite not being the biggest player on the planet, Bonaci still puts plenty of thump into baseballs. He has excellent plate discipline that translated across both levels, albeit in a small sample at Double-A. He could be one of the better hitters in the Fall League. 


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