When A.J. Preller gave up a huge package to land closer Mason Miller before the 2025 trade deadline, the trade didn’t make much sense. It now looks even worse in hindsight.
On Monday, new Padres manager Craig Stammen revealed the team plans to keep Miller in the bullpen this season, rather than move him to the starting rotation. The 27-year-old broke into the big leagues as a starter for the Athletics before an elbow injury forced him into a bullpen role.
Hours before the 2025 deadline, Preller, the Padres president of baseball operations, acquired Miller and lefty JP Sears from the A’s in exchange for four prospects: infielder Leodalis De Vries, and pitchers Braden Nett, Henry Baez, and Eduarniel Núñez.
The centerpiece of the deal was De Vries, a 19-year-old shortstop with generational tools who has already reached Double A. In 21 games at Midland after the trade, the switch-hitter slashed .281/.350/.551 with five home runs and 16 RBIs. To repeat: De Vries is 19 years old. He’s widely considered a top-five prospect in the game.
Nett was also a big part of the deal. The 23-year-old righty is a borderline top 100 prospect who is nearly major league-ready. In 24 starts at Double A in 2025, Nett went 6–7 with a 3.75 ERA, 1.47 WHIP and 116 strikeouts against 48 walks in 105 2/3 innings. He features a four-pitch mix with an upper-90s fastball and a devastating slider.
Meanwhile, Baez and Núñez are pop-up, high-velocity guys who could wind up being useful arms, but there’s a wide variance in potential outcomes for each.
It was a strange trade at the time, as San Diego already had one of baseball’s best bullpens and an All-Star closer in Robert Suarez. Given the package the Padres surrendered to land Miller, most expected them to turn him into a starter. Simply put, that’s not the type of prospect haul a team gives up for a guy it expects to throw 60 to 70 innings a year. That’s the deal you make for an ace starting pitcher.
Even with that in mind, moving De Vries under any circumstances made little sense for a franchise desperately in need of both offense and cheap players. He could have been a cornerstone of the lineup for years at a below-market contract. Instead, he’ll be starring for the A’s. Additionally, San Diego has several open spots in its starting rotation to fill, and Nett could have taken one during the 2026 season.
On the bright side, Miller was electric after joining the Padres. In 22 appearances during the regular season, he posted a 0.77 ERA and 0.73 WHIP while striking out 45 and walking 10 in 23 1/3 innings. In two postseason games, he was even better, racking up eight strikeouts and allowing no hits or walks in 2 2/3 innings. Despite those gaudy numbers, it did feel like a limited impact due to the constraints of being a reliever.
UNHITTABLE STUFF
— MLB (@MLB) October 1, 2025
Mason Miller makes quick work of the Cubs lineup! #Postseason pic.twitter.com/hWGAAhyYq9
Now that we know Miller likely won’t be starting in 2026, the trade to land him looks like a mess for Preller & Co.
Over the years, Preller has gained a reputation around baseball as a guy who is willing to severely overpay to get his guy. Most of those all-in deals have wound up backfiring on San Diego.
In 2020, he made two of them. On August 30 of that year, he sent Ty France, Andrés Muñoz, Taylor Trammell and Luis Torrens to the Mariners for Austin Nola, Dan Altavilla and Austin Adams. A day later, he shipped Josh Naylor, Austin Hedges, Cal Quantrill, Gabriel Arias, Owen Miller, and Joey Cantillo to Cleveland for Mike Clevinger, Greg Allen and Matt Waldron.
The Padres lost both of those trades. Badly.
On August 2, 2022, Preller sent CJ Abrams, MacKenzie Gore, James Wood, Robert Hassell III, Jarlin Susana, and Luke Voit to the Nationals for Juan Soto and Josh Bell. Since that time, Abrams, Gore, and Wood have all become All-Stars, while Susana is now a top 100 pitching prospect.
Soto played a total of 214 games for the Padres before being traded to the Yankees.
Those are just three of the many huge deals Preller has swung over the years in which he has given up a boatload of prospects for disappointing returns. It wouldn’t be shocking if the Miller deal is next on the list.
Preller is truly at his best working on the margins and acquiring undervalued players. He landed Fernando Tatis Jr. for James Shields, got Blake Snell and Joe Musgrove for muted returns, and landed two-time All-Star Jake Cronenworth and Tommy Pham for Hunter Renfroe and Xavier Edwards. That level of deal is his sweet spot.
Preller being all-in all the time has certainly made the Padres fun to watch. They have been consistently relevant for the first time in franchise history. But that strategy hasn’t been overly successful on the field.
Since Preller took over as the team’s general manager in August 2014, the Padres have reached the playoffs four times. The closest they have gotten to a World Series was a 4–1 series loss to the Phillies in the 2022 NLCS. Yes, they’ve been to the postseason in four of the past six seasons, but given their massive payroll, that should be expected.
In 2025, San Diego swung five trades and shipped out 12 prospects. They failed to make it out of the wild-card round.
With an aging, expensive roster, the Padres will eventually need to build through their farm system, at least to a degree. Constantly pushing in the team's chips has cost San Diego dearly, as a painful number of former prospects have gone on to become really good players.
Preller needs to get creative to build in the short and long term. Planning for the next three months instead of the next three years has led to deals like the one made for Miller.
More MLB on Sports Illustrated
This article was originally published on www.si.com as Padres’ Mason Miller Trade Makes Even Less Sense Now.