Mariners mid-round pick an interesting sleeper to watch
Mariners 2025 draft picking showing well early.
As if the Mariners’ riches in the pitching department weren’t already vast.
Seattle selected nine pitchers in the first 11 rounds of the Draft last July, and while most of the audience is focused No. 3 overall pick Kade Anderson, fourth-round pick Mason Peters, and sixth-round pick Lucas Kelly, there’s another name to track.
Right-hander Jackson Steensma is a name to watch. He missed his entire junior season at Appalachian State in 2025 after having UCL surgery, but the Mariners made him their ninth-round pick,, anyway.
Steensma stands 6-foot-4 and about 245 pounds, and has a chance at four major-league pitches. He’s sitting 91-94 mph so far in 2026, showing some arm side run from a short, three-quarter slot. His best secondary is a low-mid 80s slider with late break and some depth. He’s generating nearly 50% whiff rate on the pitch in his four starts.
Steensma also has a sharp curveball at 76-79 mph, and a mid-80s fading changeup. All three secondaries have flashed average or better, and the California League has been no match.
Sunday was Steensma’s deepest outing. He went four frames, allowing two hits and a run. He did not walk a batter and struck out seven. For the season, he’s allowed three hits and a walk over 10 innings. He’s struck out 17 of the 34 batters he’s faced. For the mathematically challenged, that’s half. :)
The 22-year-old currently profiles as a depth starter, but his fastball has firmed up since the start of the season and there may be a little more velocity in the tank. He repeats a compact delivery pretty well, and projects to throw plenty of strikes.
Steensma is certainly on an innings limit this season that isn’t likely to allow a natural, full workload, but he’s making such quick work of Single-A so far, the Mariners may have no choice to but to challenge him in the Northwest League before he hits the end of his runway.
