Scouting Report

Scouting grades: Fastball: 50 | Curveball: 60 | Slider: 50 | Control: 50 | Overall: 40

An all-state performer during his Texas high school days, Peters began his college career at Temple Junior College. After two years there, he moved on to Dallas Baptist University where he earned second-team all-Conference USA honors. Pitching mostly in relief, he led the Patriots with four saves. He also made four starts down the stretch, highlighted by a 10-strikeout six-inning performance as part of a combined no-hitter against Liberty on the final day of the regular season. He pitched well in Regional action before the Mariners took him in the fourth round of the 2025 Draft and signed him for a below-slot $550,000 bonus.

While Peters doesn't have a huge track record, the Mariners think the 5-foot-11 athletic left-hander might have the chance to start. His repertoire begins with a solid four-seamer with good ride up in the zone that sits around 93 mph and has been up to 96. He has two distinct and effective breaking pitches behind the heater. His upper-70s curve elicited a 44 percent miss rate in college in 2025, per Synergy, and he differentiates it from his sweepy low-80s slider, which he doesn't throw as often or as consistently.

With a solid and repeatable delivery and arm stroke, Peters has shown he is capable of finding the strike zone with all of his pitches. In order for him to start, he's going to have to find a changeup that works and show he can handle a rotation workload. Worst case, he has a pretty high floor as an effective lefty reliever with three useful pitches.

Transactions

Team	Date	Transaction
	08/04/2025	LHP Mason Peters assigned to ACL Mariners.
	07/19/2025	Seattle Mariners signed LHP Mason Peters.
	07/02/2025	Chatham Anglers released LHP Mason Peters.
	06/14/2025	Chatham Anglers activated LHP Mason Peters.
	06/14/2025	Chatham Anglers activated LHP Mason Peters.
	01/23/2025	LHP Mason Peters assigned to Dallas Baptist Patriots.