Expanded rosters change Major League Baseball in a big way in the month of September. The ability to carry up to 40 players on the big-league team gives clubs the opportunity to do much more than when they are limited to 25 players. They can load their bullpen with every conceivable matchup; pile up potential pinch hitters; and, for clubs out of contention — and even a few teams still in it — expanded rosters offer teams the chance to assess some of their top prospects.
Here’s a list of 12 top prospects who have already been called up to the majors in either August or September that are worth watching when they get opportunities down the stretch.
Lucas Giolito, SP, White Sox
Giolito arrived in August — not for his MLB debut, which he’d already made in 2016 for the Washington Nationals, but for a stint with the White Sox that may well prove permanent. It sure looks that way based on his first five starts. He has a 2.56 ERA, 26 strikeouts in 32.2 innings, and two very strong performances against the Detroit Tigers and Tampa Bay Rays, the latter featuring 10 strikeouts in seven innings. Giolito doesn’t quite have the same reputation he had when he was a Nationals super-prospect, but he clearly has something to offer at this level. He could prove the Nats foolish for trading him in the Adam Eaton deal.
Jack Flaherty, SP, Cardinals
A former high school teammate of Giolito at Harvard-Westlake in Los Angeles, Flaherty is a strong prospect, though he hasn’t enjoyed as much early success as Giolito. The 21-year-old was thrown right into the fray for St. Louis, coming up at the end of August immediately after the Cardinals dealt Mike Leake to the Seattle Mariners. The youngster relies on a fastball-changeup combination to get hitters out, and he very much did so in the minors, with a 2.18 ERA across 25 starts at AA and AAA in 2017. While he has struggled a bit to start his big league career, the potential is there for all to see, as he’s fanned 13 batters in 13.1 innings so far.
Rhys Hoskins, 1B/LF, Phillies
You were likely already introduced to Hoskins when he homered in five consecutive games for the Phillies in mid-August. His pace slowed down somewhat, but he really picked up the power again in the last week and is looking like a legitimate future star. Hoskins has a .310 average, 17 home runs, and impressive plate discipline to the tune of 24 walks in 33 games. He already looks the part of a slugger and is definitely worth keeping an eye on.
J.P. Crawford, infielder, Phillies
Long regarded as one of baseball’s very best prospects, Crawford’s star has dimmed after a 2017 season in which he struggled at AAA for a second straight year, hitting an underwhelming .243. He’s still earned a callup in spite of this, thanks largely to a hot second half in which he boosted his power numbers. The former first-round pick hasn’t offered much yet, but the tools that made Crawford such a highly-regarded prospect still exist. Even in his struggles, Crawford has showed an ability to get on base plus a bit of pop. After playing shortstop his entire minor league career, Crawford has moved around the infield with the Phillies, mostly playing third. He’s starting to look better at the plate as he smacked three doubles in his first two games against Miami.
Victor Robles, CF, Nationals
Nobody was expecting to see Robles called up, but he’s here, and he was immediately thrown into the lineup for Washington, picking up a double in his debut on Sunday. The uber-talented 20-year-old outfielder had only played 37 games at the AA level, but he hit .324 there after comprehensively conquering A-ball, so the Nationals wanted a look. A top-10 prospect on some lists, the speedy youngster might just get a chance to play for Washington down the stretch, as the team has already clinched their division and only has home-field advantage left to play for.
Walker Buehler, RP, Dodgers
One of baseball’s most highly-touted pitching prospects, Buehler figures to work out of the bullpen in lower-stress environments down the stretch for the Dodgers. A consensus top-20 prospect in the entire sport, this highly-touted pitcher started the season in A ball and promptly blew past every level, though AAA tripped him up a bit. Overall, though, he struck out 125 batters in just over 88 innings across three levels of the minors in 2017. He also pitched two scoreless innings with two strikeouts in his big league debut, though he was roughed up badly by the Rockies in his latest appearance. Big things are in his future.
