Padres got more than just a closer when they acquired Mason Miller from Athletics

Shoulder trouble limited Mason Miller to just six starts in his first full year of pro ball. He and his triple-digit heat still needed just two starts the following year - one for Double-A Midland and one for Triple-A Las Vegas - before the Athletics called him up for his big-league debut.

Four starts later, Miller's elbow was hurting and the A’s were thinking about his long-term future.

The 2023 season ended with the 6-foot-5 right-hander in the bullpen.

His only apprehension was that the only routine he'd ever known - going back to both Waynesburg College and Gardner-Webb - was as a starting pitcher.

"I think the decision behind it was sound for health reasons," Miller recalled. "…. But I always looked at myself as a starter to that point, so that was probably the biggest hurdle."

He's been a reliever ever since.

But Miller clearly was hardly "just a reliever" - as it was put in some circles - when the Padres gave up their top prospect in last summer's deadline deal with the A’s.

No pitcher in baseball has thrown more fastballs at 102 mph or harder since the start of the 2023 season than Miller. He’s one of just five pitchers to top 104 mph in that window. Yet it was Miller’s slider that was emerging as baseball's most valuable pitch when the Padres circled the one-time All-Star as a potential bullpen ace for years to come.

The A’s, who open a three-game series against the Padres on Friday at Petco Park, certainly knew what they had. It's why shortstop prospect Leo De Vries had to headline any return for Miller, who is under team control through 2029.

"My reaction has always been when we trade prospects away for established major league players, that it’s a good thing for us," said Craig Stammen, who was a special assistant to the Padres’ big-league coaching staff and baseball operations before taking over as the field manager this year. "You can’t predict a prospect, no matter how good or how highly rated they are, because we’ve seen it go the other way. But you have a better idea of predicting guys that have had success in the major leagues, and especially Mason, our scouts probably rated him as the No. 1 closer in all baseball, and so to make a strength that we already have even greater was probably the reason for doing it."

To be clear, more players were involved in last year’s deadline swap.

Also coming the Padres' way was left-hander JP Sears, who made a handful of starts in the majors after the trade but is now struggling to a 6.20 ERA at Triple-A El Paso.

The A’s also received right-handers Braden Nett, Henry Baez and Eduarniel Nuñez. Injuries have limited Nett and Baez to a combined three starts in the minors this season, and Nuñez was sold to the Orioles last week for cash.

All three pitchers also represent found money for the Padres: Nett signed as an undrafted free agent, Baez signed for $125,000 as an international amateur and Nuñez was a minor-league free agent.

De Vries is the player the Padres could regret trading away.

The switch-hitting shortstop signed for $4.2 million as one of the top prospects in the 2024 international amateur period, hit 11 homers in his Age 17 season that year at low Single-A Lake Elsinore, hit 15 more last year and has five homers and a.788 OPS to start this year as the youngest player in the Double-A Texas League.

Both Baseball America and MLB.com have the 19-year-old De Vries ranked No. 2 in their top-100 prospect rankings, behind only Brewers teenager Jesús Made.

Stammen watched De Vries' development the last couple of years in his front-office role, so he knew exactly what the Padres were giving up. A veteran of 13 big-league seasons, most of them in a bullpen, Stammen also knew what the Padres were trying to do by dropping Miller into the back of their bullpen.

"We gave up a lot for Mason, and we felt really good about the player that we were getting in return and having control over him for a few years," Stammen said. "And he’s definitely lived up to the billing and been everything that we’ve wanted and needed.’

Indeed.

Miller is 15-for-15 in save opportunities, one off the MLB lead. His franchise-record scoreless streak (34 ⅔ IP) saw his Fielding Independent Pitching - which measures how well a pitcher is doing based only on what he controls - sitting as low as minus-1.66 as he struck out 19 of the first 22 batters he faced. To date, he's struck out an MLB-best 51.7% of the batters he's faced and leads the majors in expected ERA (0.97), expected batting average (.095), average exit velocity (81.7 mph), whiff rate (52.4%) and hard-hit rate (12.1%).

"He's the best in the game," Dodgers manager Dave Roberts said after Miller stranded two walks in the Padres' 1-0 win on Monday.

Padres president of baseball operations A.J. Preller has made a habit out of trading for back-end arms to shorten games, acquiring Trevor Rosenthal in 2020, Josh Hader in 2022, and Tanner Scott and Jason Adam in 2024.

He struck gold with Miller.

The closer allowed a home run in his second appearance as a Padre after the trade and wasn't touched for a run again until April 27 of this year. In between, he set the franchise’s scoreless streak, struck out eight in 2⅔ scoreless innings in the NL Wild Card Series at Wrigley Field and 10 in four no-hit innings for Team USA in the World Baseball Classic.

This year, Miller anchors the Padres' “victory formation.” San Diego is 21-1 when leading after seven innings and 22-0 when leading after eight innings. The team's bullpen has been an equalizer for an offense that’s tied for last in OPS (.658) and a rotation that ranks 25th in innings pitched (236⅔).

"It's tough," Roberts said of the Padres' bullpen. "(Adrián) Morejón's throwing the ball well. Adam's throwing the ball well. Obviously, they have Miller in the back end. The last handful of years, they've always had a good pen. When they have a lead, they don't really relinquish it too often.

"You know the numbers. When they're ahead in the seventh inning, they don't lose."

It's one reason why conversations about moving Miller back into the rotation last offseason never had much momentum. He's been healthy as a reliever, throwing baseball's best fastball and slider in short bursts and anchoring baseball’s most formidable bullpen.

"I don’t think I was ever really that close to being a starter here," Miller said. "It’s like a fun idea, but it doesn’t make sense for me.”

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This story was originally published May 21, 2026 at 3:51 PM.