The final month of the MLB regular season has arrived, and with that comes roster expansion from 25 to 40 players.

For contenders, it’s a chance to add one last wave of reinforcements for the stretch run, generally in the form of additional bullpen arms and bench bats.

Corey Seager proved that September call-ups are capable of making a real impact last season, though, when he took over as the Los Angeles Dodgers’ everyday shortstop over the final month.

For non-contenders, it’s an opportunity to get an up-close look at some of the minor league talent who may be ready to step into a more prominent role the following season.

Zach Davies turned heads after joining the Milwaukee Brewers rotation in September last year, parlaying that into a spot on the team’s staff in 2016.

Now that teams have made the first wave of call-ups this season, let’s take a look at some of the notable prospects joining the MLB ranks and take a crack at predicting whether they’ll boom or bust down the stretch.

Here’s how we defined those two categories:

  • Boom: A prospect who makes a legitimate impact, whether it’s in a starting role or as a key bat off the bench or an arm in the bullpen.
  • Bust: A prospect who fails to make a legitimate impact due to lack of playing time or poor performance.

These are not meant to be long-term predictions for what type of future these players will have; it’s simply a look ahead to how they might fare in September.


Note: To be considered for this list, a player must still have rookie eligibility. That left guys such as Byron Buxton, Cody Reed, Dalton Pompey and Kevin Plawecki excluded from the conversation.

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