Mariners Sign Scott Effross, Add Former Yankees Reliever To Bullpen Mix
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The Mariners have added Scott Effross to their bullpen mix. It’s an interesting addition that literally approaches pitching from an entirely different angle. He’s a sidearmer in a bullpen the Mariners like to fill with power arms. His sinker averaged around 89 mph in his last major league stint. The appeal with him is the different approach.
This is something taken out of the Rays' handbook. Mixing in a different arm angle and varying speeds can keep a lineup off-balance. We don’t know if we’ll see him in a Mariners uniform this season, but his major league experience gives him pretty high odds.
Hitters are being asked to solve entirely different geometry. He drops his arm slot, releases the ball from the side and forces hitters to track pitches traveling across the plate instead of bearing down from a more traditional release point.
Scott Effross Gives The Mariners Bullpen A Completely Different Look
His sinker has a good-arm side run. His sweeper breaks in the opposite direction. And his changeup gives him another option against lefties. That was the formula behind Effross’ breakout in 2022.
While pitching for the Cubs and the Yankees, he posted a 2.54 ERA with 62 strikeouts and 15 walks through 56 2/3 innings. Opponents only managed a .214 batting average and a .295 slugging percentage when facing him. The Yankees liked the profile enough to send the Cubs pitching prospect Hayden Wesneski for Effross at the deadline.
Effross was especially effective against left-handed hitters, holding them to a .127/.225/.211 slash line. That version of Effross would be a great fit with Seattle. The only problem, that was 2022.
Effross underwent Tommy John surgery after that season and missed 2023 in its entirety. He also had back surgery which further complicated his return. Then a hamstring strain shut him down in 2025. After returning last season, he allowed 10 earned runs across 10 2/3 innings.
His work with Triple-A Toledo this season has been better, but not dominant. He posted a 4.01 ERA, a 1.34 WHIP and 28 strikeouts across 33 2/3 innings. Now he’s 32 with a velocity that continues to decline. His recent results do not demand a major league opportunity, but the Mariners love a good reclamation project.
The most important question is whether his sweeper still creates enough separation from the sinker. At 89 mph, Effross has little margin for error. He needs to command the zone if he wants a real shot. The Mariners can evaluate all of that in the minors without immediately using a 40-man roster spot.
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Tremayne Person is the Publisher for Mariners On SI and the Site Expert at Friars on Base, with additional bylines across FanSided’s MLB division. He founded the Keep It Electric podcast in 2023 and covers baseball with a blend of analysis, context, and a little well-timed side-eye just to keep things honest. Tremayne grew up a Mariners fan in Richmond, Va., and that passion ultimately led him to move to Seattle to cover the team closely and become a regular at home games. Through his writing, he connects with fans who want a deeper, more personal understanding of the game. When he’s not at T-Mobile Park, he’s with his dog, gaming, or finding the next storyline worth digging into.
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