How Joe Mack has changed the Marlins defensively since debut

MIAMI, FL—Following Tuesday's Miami Marlins win over the Arizona Diamondbacks, catcher Joe Mack sent a message to the entire league: "I want them to steal. I'm hoping that they steal. I'm like, 'Please run.' It's my favorite part of my game and I know my ability to throw people out and get a guy off scoring position."

Throughout the 2025 season and continuing through the first month or so of 2026, the Marlins struggled mightily against opposing base-stealers. Mack's call-up immediately flipped that weakness into a strength. The rookie has thrown out 10 runners on 26 attempts, ranking in the 90th percentile of MLB catchers in caught stealing above average, per Baseball Savant. His combination of pop time (1.89 seconds) and accuracy is elite despite his limited experience.

Mack claimed another victim on Tuesday against the Diamondbacks when he threw out Geraldo Perdomo in the top of the second inning. On a night when Marlins starter Max Meyer allowed more traffic on the bases than usual, that extra out helped him work into the sixth inning.

"It takes a little bit more pressure off the pitcher, and they can pitch a little bit more loosely," Mack told Fish On First.

Amongst the runners that Mack has thrown out include Chandler Simpson (96th percentile sprint speed), Nasim Nuñez (97th percentile sprint speed) and Jacob Young (95th percentile sprint speed).

Manager Clayton McCullough has leaned heavily on Mack—prior to Wednesday's day off, he had caught seven consecutive complete games. The Marlins won six of those seven, allowing only 3.3 runs per game during that span.

"Someone like Joe has the ability to make up for some pitchers that are a little slower...He's thrown out some real runners and come up with some big throws, so I think that part has really helped out on the run prevention side of things."

Defense really became a priority for Mack in 2024. Former Marlins catching coordinator Chris Briones, who was with the organization from December 2018 until January 2026, was a big influence on him.

"He just had a lot of good things for me to hear," Mack said. "Just really connected with me very well. He would always joke with me, make me feel comfortable and make me feel out of my comfort zone as well. It was just a great experience then, and I take a lot of pride in that."

Mack has been Meyer's battery mate in each of his last six starts.

"Everyone sees it: he's got a cannon," Meyer said. "Just having him back there is awesome. He's got his feet wet now and he's been challenging well, too. He knows the game. He's able to those runners, so it's awesome having a guy back there that can do that and takes off a lot of pressure to the pitchers too in innings where you know that if they steal, there is a very good chance that they are going to get hosed, so just makes you execute a bit better."

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2,660 likes, 22 comments - fishonfirst on June 9, 2026: "JOE MACK IS UNREAL BEHIND THE PLATE 😳🔥 Joe Mack has already thrown out 10 runners this season, and his confidence is...

Mack has brought a loose and fun personality to the Marlins clubhouse that his teammates appreciate, in particular starting pitcher Sandy Alcantara. Alcantara has called Mack a Gold Glove-caliber catcher and continuously praised him."

"Just hearing that from him, especially a Cy Young Award winner and great pitcher through and through, is awesome," Mack said. "Bunch of these guys are also awesome pitchers. I'm just here to help them be their best selves, and if I can do that by catching the ball, blocking the ball, throwing guys out for them, then that's awesome. If I can also do that, helping them by talking with them, making them laugh or making them lock it in a little bit more, whatever it may be, then great."

As a bonus, Mack has settled in as a hitter as well following a very slow start in that department. So far in the month of June, he is slashing .391/.417/.565/.982 with one home run and seven RBI. His overall wRC+ is 75.

"I think it's lowering my hands a little bit to be more consistent and more short with my load," Mack said. "I think that's something that helps me be more consistent throughout and also just maintaining the backside and opposite part of the field is a big part of my game. When I'm going hot over there, pull-side stuff will happen."

RBI double for Joe Mack extends the Marlins' lead, 2-0

He drove in Esteury Ruiz#Marlins pic.twitter.com/oELl03Uf5W

— Kevin Barral (@kevin_barral) June 6, 2026

Thanks to his defense, Mack is already making a positive impact for the Marlins. If he continues to trend in this direction offensively and hit like an average catcher—MLB average for the position is a 88 wRC+—it would make it clear that the franchise has found its long-term solution behind the plate.