MLB Prospect Watch: Four young players to watch when rosters expand in September

On Friday night, Washington Nationals right-hander Cade Cavalli will make his big-league debut against the Cincinnati Reds. Cavalli, a former first-round pick, will be the latest notable prospect to reach the majors this season. He’s unlikely to be the last.

It used to be that top prospects debuted at a few given intervals. Opening Day for the lucky few who didn’t have their service time manipulated, and then either a few weeks (if the player’s team wanted to secure an additional year of control) or months (if the player’s team wanted to avoid an extra year of arbitration) later. The new Collective Bargaining Agreement rewards teams if their players win the Rookie of the Year Award, which may change the equation for some of the game’s top prospects.

earlier this week, we explained the new dynamic by using Baltimore Orioles infield prospect Gunnar Henderson as an example. If a team believes their good prospect, like Henderson, could be in the running for the subsequent season’s Rookie of the Year Award, they can still bring them up this year — they just have to ensure the prospect doesn’t eclipse either service or playing-time thresholds that would eliminate their rookie status. The former is no longer a consideration this season, while the latter can be micromanaged, especially with rosters set to expand to 28 players on Sept 1.

So, other than Henderson, who are some players that might make the leap over the coming weeks? Here are four names to keep in mind, presented in order of perceived likelihood.

Carroll is, alongside Henderson, the name most frequently mentioned by scouts and analysts as the best prospect in the minors. He’s a center fielder who can really hit and really run, with the biggest knocks against him entailing his durability (90 of his 139 professional appearances have come this season) and some in-zone swing-and-miss issues he battled with earlier this year . He’s slashed .294/.401/.529 with six home runs and 11 stolen bases in 30 Triple-A games this season, and it seems like a given that the Diamondbacks will reward him with a big-league cameo before September ends.

Jung, the No. 8 pick in the 2019 draft, would’ve been in the majors by now if he hadn’t torn the labrum in his shoulder in the spring. He returned to the diamond in July, and he’s spent the past few weeks in Triple-A, batting .340/.400/.800 with six home runs in 12 games. Jung has even taken to playing the field again. He’ll celebrate his 25th birthday before next Opening Day, so the Rangers would be justified in pressing down on the accelerator to find out if he’s ready to assume their third-base job.

Think of Frelick as Carroll Lite. He’s also a diminutive center fielder with a track record hitting anywhere and everywhere, he just doesn’t have the same power potential. Frelick has batted .332/.405/.472 with 34 extra-base hits and 17 stolen bases across three levels this season. If the Brewers want to improve their vibes (and their playoff odds), they could do worse than installing Frelick in center field for the home stretch.

There are a number of other worthy candidates out there, but we’re including Brown because his season deserves recognition. He’s struck out 31 percent of the batters he’s faced in Triple-A this season, and has done so while coercing more than 50 percent groundballs. That’ll play. Brown isn’t on the 40-player roster, but he’ll have to be added this winter for Rule 5 purposes. The Astros can save themselves the paperwork by making the move now and letting him get a look-see out of the ‘pen.