Felnin Celesten — Mariners Prospect Profile

Celesten had a terrific season, despite some struggles in Arkansas before a groin injury ended his season. Consistent contact will again be the key when he gets back at it in Double-A next April, but the switch hitter only turned 21 in September and is ahead of schedule in his development. For now, I'm not overly concerned about the defense, but it's probably a conversation for next spring and summer.

The terrific year was mostly a High-A year, and it was a genuine breakout. Celesten hit .314/.409/.534 across 364 plate appearances in Everett with a 137 wRC+, and the power arrived all at once: his isolated slugging went from .099 in Single-A in 2025 to .220, and he hit 13 home runs after totaling six across all of the previous season. June was the peak — .330/.376/.649 with seven of those homers and a .319 ISO. He also walked more than he had at any full-season stop, 12.4%, while cutting his strikeout rate to 20.6%.

Then Double-A, and the line everyone will see first: .171/.239/.268 in 134 plate appearances, a 33.6% strikeout rate, a 6.7% walk rate, and a swinging-strike rate that jumped from 12.1% to 17.8%. Both the contact and the patience went at once, which usually means a hitter chasing.

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Here is the part worth holding onto. Celesten's first look at High-A came in 11 games at the end of 2025: .158/.312/.289 with a 31.2% strikeout rate. His first look at Double-A produced .171 and a 33.6% strikeout rate. Those are nearly the same introduction. He then returned to High-A in 2026 and hit .314 with a 137 wRC+ and half again the power. The pattern so far is that the first exposure to a level looks like this, and the second one doesn't.

The stint also got worse rather than better before it ended. He hit .235/.316/.382 in July and .146/.208/.225 in August, with the strikeout rate climbing to 37.5% and the walk rate falling to 5.2%, and the season closed on August 27 with the groin injury. Worth allowing for the obvious: these things rarely announce themselves on the day they end a season, and it's reasonable to think he was something less than whole for at least part of that final month. That doesn't erase the strikeout rate, but it belongs next to it.

One thing his line does quietly: he stole 25 bases in 32 attempts across 2026, 18 of them in 22 tries at High-A. That is a legitimate weapon that hasn't gotten much attention, and it held up at both stops.