Gregory Pio — Mariners Prospect Profile
Mariners center fielder, No. 8 in the September 2026 rankings. Scouting reports, development notes and level-by-level analysis from Jason A. Churchill.
Pio continues to impress with his ability to put the ball in play, and I have received reports of his willingness to hit the ball where it's pitched and to adjust his approach with two strikes. He's an above-average runner with plus bat speed and a chance to stay in center, and he's shown more polish this summer in the DSL than some expected.
The number that carries a first professional summer at 17 is this one: 36 walks, 33 strikeouts. Pio drew free passes 17.5% of the time and struck out 16.0%, and the distribution matters as much as the rate. He went without a strikeout in 21 of his 47 games, struck out more than once in only seven, and never struck out three times in a game all season.
The two-strike adjustments you're hearing about show up in that spread. So does the contact profile — 15 extra-base hits, and on June 2 against Texas a 4-for-5 night with two doubles and two triples, which is a specific kind of day. Nobody hits two triples by pulling the ball.
Jason A. Churchill
The speed is not a projection. He stole 18 bases in 21 attempts, an 86% success rate, with four multi-steal games. And the organization played him in center field in 38 of his 47 games, five more in left.
He also reached base in 42 of 47 games, including a 12-game streak from June 26 through July 16.
Two things keep it honest. The season was front-loaded: he hit .346/.444/.568 in June with 11 of his 15 extra-base hits, then .196/.300/.255 across 14 July games with exactly one. The bat came back partway in August, and notably the approach never left — his walk rate climbed to 25.5% in that final month even while the hits weren't falling.
And the overall line produced a 106 wRC+, which is barely above average for the level. The Dominican Summer League is a hitting environment, and a .275 average there is not what it would be anywhere else. The production is real for a first-year player at that age; it is not yet separation from his peers.
