Oswald Peraza
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September has arrived, and that means rosters have expanded for the final few weeks of the MLB regular season. In the past, teams could activate their entire 40-man roster in September. Now, teams can only add two extra players to their roster on Sept. 1. MLB and the MLBPA agreed to change the September roster expansion rules a few years back and they went into effect in 2021.

So many September call ups are the extra reliever who's been going up and down all season, or a spare bench guy who can pinch-run or play multiple positions. Depth players who doesn't play often. Some are top prospects, though. They come up and are put in the lineup in September, giving them a chance to strut their stuff in the season's final month. It's a fun time of year.

The Diamondbacks and Orioles got a head start on prospect call ups earlier this week, when they summoned outfielder Corbin Carroll and shortstop Gunnar Henderson, respectively. Carroll and Henderson are arguably the two best prospects in baseball, and they were called up before rosters expanded on Sept. 1. They technically aren't September call ups.

Here are a few prospects called up on Sept. 1 who could impact the various postseason races. To be clear, we're looking at players who were called up on Sept. 1 (so not Henderson, who was called up on Aug. 31), and prospects only. The Dodgers used one of their extra September roster spots to activate Clayton Kershaw off the injured list, but he's not a prospect, so he doesn't count.

So, with that in mind, here are four prospects who are September call ups and could make a difference in the postseason races as the regular season winds down. The players are listed alphabetically.

IF Jonathan Aranda, Rays

Second baseman Brandon Lowe hit the injured list earlier this week and Tampa's first base production has been lacking pretty much all season. Aranda, owner of a .318/.394/.521 batting line in Triple-A, can play those two positions as well as third base, and he's even dabbled in left field. It won't be difficult to get Aranda's bat in the lineup regularly with that versatility, and his lefty bat will help replace some of the punch the Rays lost when Lowe went down. Aranda went 6 for 16 (.375) in seven games with Tampa earlier this season. It was his MLB debut. The Rays currently sit in the first wild-card spot and still have a chance at the AL East title.

LHP DL Hall, Orioles

DL Hall
BAL • SP • #24
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A starter by trade, the O's appear set to use the hard-throwing Hall out of the bullpen these last few weeks. He made his MLB debut last month, allowed five runs in 3 2/3 innings in a spot start, then was sent back to Triple-A to transition to the bullpen. Hall struck out 11 in 6 2/3 innings across four Triple-A relief appearances and could be a fierce multi-inning relief option for Baltimore as they look to stun the world and secure the third and final American League wild-card. They enter Friday only 1 1/2 games out. Hall has a 4.70 ERA in Triple-A this season but did strike out 125 batters in 76 2/3 innings.

SS Oswald Peraza, Yankees

The Yankees have received subpar production from stopgap shortstop Isiah Kiner-Falefa this season, and they appear poised to give Peraza, a consensus top-100 prospect, a shot at the job these next few weeks. Peraza has authored a .291/.365/.511 batting line in Triple-A since June 1 and has 19 homers this season. Kiner-Falefa has one. At minimum, Peraza should provide more over-the-fence power and could be a rather significant upgrade on both sides of the ball if he hits the ground running in his MLB debut. New York has crashed hard these last few weeks, as their AL East lead has whittled down from 15 1/2 games to only six.

OF Esteury Ruiz, Brewers

Acquired from the Padres in the Josh Hader trade, Ruiz currently leads the minors with 70 stolen bases, so at the very least he will provide the Brewers with an elite pinch-running option. Ruiz can hit, too, slashing .320/.427/.442 in Triple-A this season. Center field has been a problem for Milwaukee all season, and while recent call up Garrett Mitchell is getting a chance to run with the job now, Ruiz could be a factor at some point as well. He went 6 for 27 (.222) in 14 games with San Diego during his MLB debut earlier this season. The Brewers are currently three games behind the third and final National League wild-card spot.

Other notable September call ups

Aranda, Hall, Peraza, and Ruiz are the prospects called up on Sept. 1 who are most likely to make a difference in the postseason races. They're hardly the only prospects to come up when rosters expanded, though. Here are a few other notables, listed alphabetically.

RHP Hunter Brown, Astros: Houston has an 11-game lead in the AL West and a five-game lead for the AL's best record, so they're sitting pretty. Brown is a starter and threw 106 innings with a 2.55 ERA and 134 strikeouts in Triple-A this season, though the Astros are expected to use him out of the bullpen, at least initially. A few spot starts down the line, perhaps when the Astros are getting their postseason rotation lined up, could be in the cards. This will be Brown's MLB debut.

1B Spencer Torkelson, Tigers: It has been a disastrous season for the Tigers and Torkelson, the No. 1 pick in the 2020 draft. He hit .197/.282/.296 in 83 games with Detroit, was sent down to Triple-A in July, and he didn't exactly tear the cover off the ball there either (.229/.348/.389 in 35 games). The Tigers are well out of the race and have nothing to play for these last few weeks, though they need to see something from Torkelson in September.

3B/LF Miguel Vargas, Dodgers: Vargas has had a loud season in Triple-A, hitting .304/.404/.511 with 32 doubles, 17 home runs and 16 stolen bases. He's also played some first and second base in addition to third and left, so he's versatile and there's thump in his bat. The Dodgers have an enormous lead in the NL West (18 games) and a nice advantage for baseball's best record (6 1/2 games), so they're not playing for much these last few weeks. That said, Vargas could hit his way into the postseason roster conversation.

LHP Ken Waldichuk, Athletics: Acquired in the Frankie Montas trade with the Yankees, Waldichuk has struck out 34.5 percent of the batters he's faced this year, the eighth-highest rate in the minors. He has a 2.84 ERA in 95 innings split between Double-A and Triple-A this season. The A's are well out of the postseason race, but they have a chance to play spoiler in September because they have series remaining with the Braves, Mariners, Mets, Orioles and White Sox. Waldichuk made his MLB debut Thursday, allowing one run in 4 2/3 innings against the Nationals.