#3: Mariners A-Ball RHP Juan Then – 5 GS, 7.11 K/9, 3.79 BB/9, 4.26 ERA, 4.87 FIP
Then really hasn’t struggled all that much this season, he makes the list largely due to his prospect ranking and the fact that there aren’t a lot of Mariner prospects who have struggled. Fangraphs currently has Then as the No. 11 prospect on their list, and MLB.Com has him as the Mariners No. 8 prospect in the system.
Then’s early struggles aren’t terribly surprising considering he is only 21 and has only thrown 65 innings above Rookie ball. The walks will likely come down with experience, but the low strikeout numbers are a little concerning, especially considering Then sits in the high 90’s with his heater.
What could ultimately be in store for Then, is a move to the bullpen. The heat is there, but he may not have enough of an arsenal to make it as a starter. And it has to be considered that the Mariners have a lot of potential starting pitchers in the system. Logan Gilbert already looks like an MLB pitcher, and both Hancock and George Kirby have been dominant as prospects. It’s not totally out of the question for Then to take the Edwin Diaz route and eventually move to the bullpen.
If Then can continue to develop the fastball and slider combo and add a more consistent change-up, then he should be fine. But as of right now, Then’s 2021 campaign in Everett has been a tad underwhelming.