Miles Mastrobuoni Embracing Utility, Do-Everything Role For Seattle Mariners

SEATTLE — With the Seattle Mariners down 3-2 to the Kansas City Royals in the bottom of the ninth on Thursday, Miles Mastrobuoni stepped to the plate to pinch-hit for third baseman Ben Williamson.

Mastrobuoni hit a single to give the Mariners the game-tying run on base and the go-ahead run at the plate. He was ultimately left stranded at third and the M's lost, but Mastrobuoni's hit was the most recent example of him stepping up in his niche but valuable role with Seattle.

Thursday was Mastrobuoni's fourth base-hit in pinch-hit plate appearances this season. He's scored 17 runs in 64 games as of Friday and and has hit three doubles and a home run with 11 RBIs. He's drawn 16 walks and has slashed .248/.327/.293 with a .620 OPS. If the season were to end today, his hits, RBIs, on-base percentage and OPS would all be career-highs.

"He's had a lot of great at-bats late in games. ... He's got such a good concept of the strike zone," Mariners manager Dan Wilson said in a postgame interview Thursday. " ... That's what you want late in the game, and he's been able to do that consistently. ... He really thrives in those situations. ... There is an art to it, there's a trick to it and (he's) done a nice job at it."

Wilson also mentioned Mastrobuoni's ability to stay aggressive while not chasing in pinch-hit situations.

Mastrobuoni has a 19% chase rate, 15.3% whiff rate, 15.7% strikeout rate and 10.5% walk rate, per Baseball Savant. All those marks rank in the upper percentile of the league.

"Mindset-wise, it's just 'have a good at-bat,'" Mastrobuoni said in a pregame interview Friday. "Get on base any way that you can. On the flip side, getting ready for it, just bouncing things off (hitting coach Kevin Seitzer) and (assistant hitting coach Bobby Magallanes) down there in the cage. I've just found something that's worked to feel more game-like. Makes it feel like the game's just a little bit slower once you get up into those pinch-hit at-bats later in the game."

Mastrobuoni was acquired by Seattle in a deal with the Chicago Cubs on Jan. 14, 2025, in return for cash considerations. Beyond his late-game offense, he's been used in a utility role on defense and has played third base, second base, left field and right field for the Mariners. He's been able to provide solid defense while on the field wherever he's played.

He has two outs above average, which ranks in the 80th percentile of baseball.

"Big confidence booster, for sure," Mastrobuoni said. "They've used me in a lot of spots this year, which has been great. That's kind of how it was when coming up when I was with the (Tampa Bay Rays). There's a lot of good guys in that system, and that's something I had to move my way into. I think it helps, teams need a guy like that, so I'll be that, for sure."