10 MLB September Call-Ups Ready to Make Major Impact on Playoff Races

The final month of the 2026 MLB regular season is fast approaching, and the calendar flipping to September also means that active rosters expand from 26 to 28 players across baseball.

The days of roster swelling to as many as 40 players ended in 2021, and with the more streamlined rules, those two additional spots carry added significance for contenders looking to bolster the roster for the playoff push.

To that point, Trey Yesavage (TOR) and Connelly Early (BOS) both ended up starting playoff games last October after debuting as September call-ups.

We've highlighted 10 players who could be the headliners of this year's September roster additions, with each one offering a legitimate chance to make an impact for a contending club.

SS Franklin Arias, Boston Red Sox

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Stats: 99 G, .314/.397/.564, 47 XBH (23 HR), 6 SB

Why He's Ready: Already widely regarded as the best defensive infielder in the Red Sox system, Franklin Arias has taken his offensive game to new heights this season. His slugging percentage has climbed a staggering 176 points despite making the jump to the upper levels of the minors, and he has done it while also improving his walk rate from 7.2 to 10.7 percent.

Projected Role: With Trevor Story sidelined, the Red Sox have leaned on Andruw Monasterio as their primary shortstop for the past month. Story is on the rehab trail, but he had a 54 OPS+ in 176 plate appearances before undergoing sports hernia surgery, and he's 4-for-25 with seven strikeouts at Triple-A.

Meanwhile, Arias is batting .301/.368/.495 with 10 extra-base hits in 24 games since he was promoted to Triple-A. He has started seeing reps at second base, so there is a potential secondary path if the starting shortstop job is indeed still waiting for Story.

OF Cam Cannarella, Miami Marlins

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Stats: 80 G, .332/.433/.524, 29 XBH (13 HR), 19 SB

Why He's Ready: The No. 43 overall pick in the 2025 draft, Cam Cannarella is already knocking on the MLB door thanks to his 55-hit, 60-speed toolbox. After crushing High-A and Double-A pitching to open the year, he has a .273/.405/.384 line over 27 games since he was promoted to Triple-A while logging a healthy 15.7 percent walk rate.

Projected Role: The Marlins are 25th in the majors in runs scored (139) since the All-Star break, and they could use a spark while they pursue a wild-card berth. A year ago, Jakob Marsee provided just that when he joined the team on Aug. 1, and Cannarella could provide a similar jolt.

With Owen Caissie (51 PA, .178/.275/.289, 31.4 K%) and Esteury Ruiz (50 PA, .200/.360/.300, 36.0 K%) both struggling in August, there is a clear path for him to play his way into a regular role down the stretch.

OF Patrick Clohisy, Atlanta Braves

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Stats: 107 G, .293/.376/.466, 43 XBH (10 HR), 58 SB

Why He's Ready: Patrick Clohisy was the No. 29 prospect in a relatively thin Atlanta farm system to start the year, according to Baseball America. A .284/.390/.383 line over 21 games in the 2025 Arizona Fall League helped elevate his prospect stock, and that has carried over to a breakout 2026 campaign. In 37 games since moving up to Triple-A, he is hitting .357/.440/.512 with 13 extra-base hits and 21 steals.

Projected Role: With speed and the ability to play all three outfield spots, Clohisy is the type of player who can slot seamlessly onto the big league bench and provide value without seeing regular playing time.

That said, his stellar performance at Triple-A along with the lackluster production from Mike Yastrzemski and Lane Thomas in a left field platoon cracks the door for him to potentially seize a bigger role.

RHP Coleman Crow, Milwaukee Brewers

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Stats: 15 G, 14 GS, 3.13 ERA, 1.13 WHIP, 29 BB, 79 K, 77.2 IP

Why He's Ready: The Brewers acquired right-hander Coleman Crow in the deal that sent Adrian Houser and Tyrone Taylor to the Mets prior to the 2024 season, and he made his MLB debut in April.

He didn't find immediate success in the big leagues, but continued to thrive back at Triple-A, and with 18.2 scoreless innings over his last three starts he has earned another look.

Projected Role: While he made four spot starts earlier this season, Crow would slot into a multi-inning role in the Milwaukee bullpen down the stretch where his high-spin curveball could be a major weapon.

The Brewers figure to lean heavily on mixing and matching arms in October behind ace Jacob Misiorowski, and Crow is capable of pitching his way onto the playoff roster with a strong September showing.

RHP Ty Johnson, Tampa Bay Rays

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Stats: 18 G, 10 GS, 2.90 ERA, 0.97 WHIP, 22 BB, 80 K, 59.0 IP

Why He's Ready: The Rays acquired Ty Johnson from the Cubs in the Isaac Paredes deal at the 2024 trade deadline, and over the past two seasons he has carried a 34.6 percent strikeout rate in the upper levels of the minors. He was moved to the bullpen at the end of July in advance of a potential call-up, and he has a .161 opponents' batting average and 14.0 K/9 in 9.2 innings as a reliever.

Projected Role: Despite a more traditional starting staff than usual with Drew Rasmussen, Shane McClanahan, Nick Martinez and deadline pickup Freddy Peralta all capable of pitching deep into games, Tampa Bay has always done an excellent job fully utilizing its bullpen.

With a dynamic fastball-slider combination, Johnson has the stuff to make an immediate splash in shorter stints, with his wipeout slider a legitimate putaway pitch that could earn him some high-leverage opportunities.

RHP Bryce Mayer, Houston Astros

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Stats: 20 G, 17 GS, 2.92 ERA, 1.13 WHIP, 38 BB, 112 K, 83.1 IP

Why He's Ready: Arguably the top pitching prospect in a thin Houston system, Bryce Mayer has come a long way in a short time since going in the 14th round of the 2024 draft. After a shaky Triple-A debut on Aug. 8, he has allowed six hits and one earned run over 11.1 innings in his two most recent outings, and he increasingly looks like a finished product.

Projected Role: The Astros have often eased their young starters into the big leagues in a relief role, and with a mid-90s fastball and two solid breaking balls, he has a repertoire that could potentially play up in shorter stints.

Then again, considering how Cristian Javier (4 GS, 5.68 ERA, 19.0 IP), Peter Lambert (4 GS, 6.98 ERA, 19.1 IP) and Ethan Pecko (2 GS, 7.88 ERA, 8.0 IP) have pitched in August, a shot at the rotation is also not out of the question.

OF James Tibbs III, Los Angeles Dodgers

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Stats: 119 G, .300/.423/.559, 57 XBH (27 HR), 7 SB

Why He's Ready: The Dodgers have a wealth of exciting young outfield talent, but none is more MLB-ready than James Tibbs III, who has spent the entire 2026 season crushing Triple-A pitching. With a .360/.490/.640 line over 98 plate appearances in August, he is swinging it well enough to warrant a call-up.

Projected Role: Tibbs has yet to reach the majors largely because of the Dodgers' crowded outfield., but that changed when Andy Pages suffered a fractured hand on Aug. 21.

Tibbs is strictly a corner outfielder, so he's not a direct replacement, and Alek Thomas earned the initial call-up to fill the gap in center field. That said, there is always room for another productive bat on the roster. Tibbs could serve as a pinch-hit option for Thomas late in games, with Tommy Edman shifting from second base to center field.

1B/OF Ralphy Velazquez, Cleveland Guardians

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Stats: 106 G, .293/.379/.561, 52 XBH (27 HR), 2 SB

Why He's Ready: Over 18 games at the Triple-A level in August, Ralphy Velazquez is hitting .371/.438/.986 with 14 home runs and 27 RBI. What more really needs to be said about his MLB readiness?

Projected Role: Considering the Guardians rank 28th in the majors with 18 home runs in 22 games this month, they should be rolling out the red carpet for Velazquez to fill whatever role best suits him.

The 21-year-old fits best at first base, where he would be an immediate upgrade over deadline pickup Nathaniel Lowe, who has an 83 OPS+ in 17 games since joining the Guardians. He has also started 20 games in left field in the minors this year and would pencil nicely into the DH role as well.

One way or another, he's one of the best nine bats in the organization right now.

RHP Jaxon Wiggins, Chicago Cubs

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Stats: 15 G, 11 GS, 6.88 ERA, 1.76 WHIP, 30 BB, 44 K, 35.1 IP

Why He's Ready: A consensus Top 100 prospect entering the 2026 season, Jaxon Wiggins has struggled through a trying season that was derailed early by elbow inflammation. His 6.88 ERA and 18.3 percent walk rate don't scream immediate impact, but he was moved to the bullpen on Aug. 11 and has struck out seven of the 16 batters he's faced over four no-hit frames.

Projected Role: With a 60-grade fastball that tops out at 101 mph and a wipeout slider, it's easy to envision Wiggins pitching his way onto the playoff roster based on pure arm talent.

His spotty command makes it unlikely he will see high-leverage work, at least initially, but his swing-and-miss stuff and ability to go multiple innings have plenty of value to a Cubs team in need of additional arms.

RHP Gage Wood, Philadelphia Phillies

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Stats: 22 GS, 4.11 ERA, 1.21 WHIP, 27 BB, 117 K, 81.0 IP

Why He's Ready: Just a year removed from going No. 26 overall in the 2025 draft, Gage Wood has firmly established himself as one of baseball's top pitching prospects. He is currently pitching at Double-A, but young pitchers skipping over the Triple-A level is not uncommon, especially for a late-season debut.

Projected Role: With rookie Andrew Painter coming off seven innings of five-hit, one-run ball in his last start, any thoughts of Wood stealing the No. 5 starter job down the stretch are likely misplaced.

However, he spent his first two seasons at the University of Arkansas pitching almost exclusively out of the bullpen, and that's where he could make a bigger impact for the Phillies. In 2023, Orion Kerkering made the playoff roster after just three regular-season appearances and ended up finding his way into seven games in the playoffs, so there is some precedent.