San Diego Padres Make Incredibly Bizarre Trade For Star Reliever Mason Miller

The San Diego Padres made one of the most confusing trades in recent baseball history ahead of the trade deadline Thursday.

In a stunning deal with the Athletics, the Padres acquired closer Mason Miller and starting pitcher J.P. Sears. In return, San Diego sent consensus top-5 prospect Leo De Vries, pitcher Braden Nett, pitcher Henry Baez and pitcher Eduarniel Nunez. 

A top five prospect in all of Major League Baseball, and the number three, 13, and 17 prospects in the Padres sytem? For a reliever and a starting pitcher with an ERA over 5? 

If that sounds like a lopsided return, it's because it is. And looking closer at the trade just makes it worse.

Jun 16, 2025; West Sacramento, California, USA; Athletics pitcher Mason Miller (19) walks off the mound after retiring the last batter of the 9th inning at Sutter Health Park. Mandatory Credit: Ed Szczepanski-Imagn Images

Padres Trade Their Best Prospect For No Apparent Reason

Miller is a very good reliever, and averages over 101mph on his fastball. He gets a commensurate amount of swings and misses and has one of baseball's highest strikeout rates. He's also under team control through the 2030 season, ensuring that the Padres didn't give up their top prospect for a rental. That's the good news.

The bad news? His on-the-field results haven't actually been that great. He's had a lengthy injury history. And the inherent volatility in relief pitching makes it difficult to predict year-to-year performance. San Diego already had one of baseball's worst farm systems, and just traded arguably their only "elite" prospect for a relief pitcher. Oh, and, by a wide margin, the Padres' biggest strength this season has been their relief pitching. 

If you're wondering what in the world they were thinking, you're not alone.

To start, Miller's career ERA is a solid but unspectacular 3.12. Unsurprisingly, given how hard he throws, he can battle bouts of wildness, as evidenced by walking 4.3 hitters per nine innings this year. As is also common with hard throwing pitchers, Miller's average exit velocity is low, but his hard hit rate is high. Essentially, there's no middle ground. Hitters either make weak contact, or hit the ball extremely hard against him. This year, he's allowed an 11% barrel rate and a 41.1% hard hit rate. That barrel percentage is in the bottom 13th percentile across MLB, and his hard hit rate is also below average. 

Still, Miller's capable of dominance and sports a 39.1% strikeout rate after posting a 41.8% strikeout rate in 2024. Worth trading for? Absolutely. Worth trading a top-5 prospect at shortstop when you already have the best bullpen in baseball? No. And right now, the Padres have the best bullpen in baseball.

With active rosters factored in, the Padres bullpen collectively has a 2.73 ERA and leads MLB in WAR with 6.1, per Fangraphs. Where they do need help? On offense and with starting pitching.

Padres active starters rank 15th in MLB with 5.9 WAR. At the catching position, San Diego ranks dead last with -21 runs on offense and a -0.9 WAR. Padres left fielders have also been below average offensively and by WAR. They're starting Luis Arraez at first base, who has six home runs, a -3 batting run value, per Statcast, and ranks near the bottom of most contact quality metrics. It's a lot of empty bloop 73mph singles to left field, and even then, his expected stats show that as bad as he's been, his future performance will likely be worse. At least JP Sears has an ERA near 5 this season, and a career ERA near four and a half.

And that's what makes the Miller deal so bizarre. They gave away their best, arguably only, desirable prospect to upgrade a position they didn't need to upgrade and ignored other positions where there's obvious room for improvement. Are the Padres better today than they were yesterday? A little bit, sure. Was it worth what they gave up? Probably not. Yes, prospects often don't pan out. And sometimes they become James Wood, a former Padres prospect traded for Juan Soto, and one of the most valuable players in the sport.