A's Acquire Top MLB Prospect in Mason Miller Trade with Padres

Jul 12, 2025; West Sacramento, California, USA; Athletics pitcher Mason Miller (19) reacts after defeating the Toronto Blue Jays 4-3 at Sutter Health Park. Mandatory Credit: Dennis Lee-Imagn Images | Dennis Lee-Imagn Images

On Thursday morning, ESPN's Jeff Passan broke the news about a seismic trade that will alter the future of A's baseball.

The A's and San Diego Padres agreed on a deal that would send flamethrower Mason Miller and lefty JP Sears to San Diego in return for a haul of prospects. There were rumors circulating last night that both sides were discussing a deal after Miller did not enter the game in a save situation, and the agreement was reached before breakfast.

The main piece the A's acquired was the No. 3 prospect in MLB, Leo De Vries. At 18 years old, De Vries is already playing in High-A baseball and is ranked behind Pittsburgh Pirates Konnor Griffin and Cincinnati Reds Chase Burns in MLB Pipeline's Top 100.

The A's also acquired the Padres' No. 3 prospect, right-hander Braden Nett; No. 13 prospect, right-hander Henry Baez; and No. 17 prospect, right-hander Eduarniel Núñez.

When the news broke that the Padres would be including De Vries in the return package for Miller, the baseball world turned upside down. De Vries is regarded as a superstar in the making, which may be high praise for an 18-year-old, but it is more than warranted.

Not only is competing in High-A baseball at 18 an accomplishment in itself, but producing at the rate De Vries is, that's a whole other level. In 82 games, the highly touted prospect is hitting .245 with an OPS just under .800. MLB Pipeline praises De Vries for his knowledge of the zone, which is backed up by his 14.1% walk rate and 19.6% strikeout rate.

De Vries has surprised scouts with his pop at such a young age, having seven of his eleven home runs come from the right side in 2024 at Low-A. So far, he has eight home runs in 2025 at a higher level and has seen improvements in how he takes his at-bats.

De Vries is the prized possession and the centerpiece of the deal for Miller and Sears, but the A's acquisition of the three other pitchers deserves attention as well.

Nett, the Padres' No. 3 overall prospect, has pitched very well in Double-A this season. The 23-year-old holds a 3.39 ERA in 74.1 innings with 86 strikeouts. He does struggle with walks, having a 4.12 BB/9, which has led to concerns that he may be destined for the bullpen.

However, Nett has two plus pitches, his fastball and slider, that he pairs with the rest of his arsenal, giving him quite the bag to throw at opposing hitters. Nett has had great success the past two seasons as a starter, and the A's certainly view him as one. As a team that relies on their development, Nett could iron out his walk issues and move through the system quickly.

The final two pieces the A's acquired were two pitchers, Baez and Núńez. Baez, like Nett, has been pitching at the Double-A level in 2025. The 22-year-old holds a 1.96 ERA over the span of 20 starts and 96.2 innings. He has struck out 89 batters and only walked 31 this season. To say Baez has been lights out would be a bit of an understatement, considering his WHIP sits right at 1.00.

Núńez is the pitcher that A's fans will probably see first on the big league roster. At Triple-A El Paso this season, Núńez has pitched 12 1/3 innings without allowing a run. He started the year in Double-A and posted a 3.57 ERA before his promotion. Núńez even saw time at the MLB, only 4.2 innings, but saw some success.

He was a bit rocky during his brief MLB stint, walking four to only two strikeouts. Núńez has two pitches, both of which are plus offerings according to MLB Pipeline. His fastball is graded at 60 (20-80 scale), and he can run it up to 101, but it sits at 97-99 mph. His slider, graded as a 70, sits in the upper 80s and is his best pitch, with a lot of depth.

With Miller now out of the bullpen, the A's will be looking for their next closer. Jack Perkins may be the guy they turn to, with his three saves already on the year, but Núńez could be in that conversation as well.

The A's did very well in receiving a return package that will propel their rebuild and give them their deepest farm system in years. Parting with Miller will hurt in the short term, but as young pitchers get more action and the A's move closer to contention, this deal may be viewed as one the A's blew out of the water. Especially if De Vries lives up to the expectations and talk that is around him.