San Diego Padres’ general manager AJ Preller gave up one of the most highly-touted prospects in baseball (plus other prospects) for a pitcher who will throw one inning at most at a time.
Padres Receive: RHP Mason Miller, RHP JP Sears
Athletics Receive: SS Leo De Vries (MLB Pipeline No. 3 overall prospect), RHP Braden Nett (Padres’ No. 3 prospect), RHP Henry Baez (No. 13) and RHP Eduarniel Núñez (No. 17)
26 years old with four additional years of control after 2025, Mason Miller adds to the Padres’ bullpen not only an element of depth, but flamethrowing star power and versatility that could lift this team to new heights as they sit 3 games behind the Dodgers in the division and 3 games over the Reds in the final NL Wild Card spot.
Who is Mason Miller?
If you live anywhere other than Oakland Sacramento San Diego, you probably have only seen clips or heard mentions of a triple-digit-throwing righty on the west coast. As a Mets fan that occasionally tunes into MLB Network, I barely knew the guy–but Miller could be the reason the Padres make noise heading into October.
A former D-3 player at Waynesburg University (PA), he played a fifth year of college baseball at Gardner-Webb University in North Carolina. His stat line at Gardner-Webb–3.30 ERA and 121 strikeouts in 14 starts and 92.2 innings pitched–caught the attention of major-league scouts.
In 2021, the Oakland Athletics selected Miller with the 26th pick (97th overall) in the 3rd round, thereafter beginning his career as a starting pitcher in the minor leagues.
In 2022, he dealt with a shoulder strain that delayed his season debut until August, before pitching for the Complex League, High-A (A+), and Triple-A (AAA), making 6 starts total between the three levels:
- 14.0 IP, 3.86 ERA, 3.58 FIP, 1.56 xFIP, 50.0 K%, 6.0 BB%, 0.79 WHIP, 1.93 HR/9.
First, he struck out 25 of 50 total batters faced–not a huge sample size, obviously, but hard to ignore that dominance. Second, his 1.56 xFIP (Expected Fielding-Independent Pitching) suggests he allowed an inflated home run-rate relative to league average–again, small sample size can have this effect.
Heading into 2023, MLB Pipeline ranked Miller as the 4th-best A’s prospect–crediting his triple-digits fastball and “what is looking more and more like a wipeout slider.”
In 2023, Miller spent time at Single-A (A), Double-A (AA) and AAA, starting 7 games:
- 19.1 IP, 1.86 ERA, 3.10 FIP, 2.31 xFIP, 50.0 K%, 7.1 BB%, 0.67 WHIP, 1.40 HR/9.
So I don’t sound like a broken record, I won’t get into these numbers because a lot of the same analysis applies as of 2022–but it has to be noted he struck out half the 70 total batters he faced again!
On April 18, 2023, the A’s promoted Mason Miller to the big-league club. Unlike the current Mason Miller, rookie Mason Miller started games for the A’s. He made 6 starts at the MLB level in 2023:
- 24.1 IP, 3.70 ERA, 3.17 FIP, 4.74 xFIP, 26.7 K%, 10.9 BB%, 1.15 WHIP, 0.37 HR/9
Those are really good numbers to have in the first 6 starts of your MLB pitching career. Unfortunately for Miller, he landed on the IL on May 11 (after 4 starts) with right forearm tightness before being shut down with a mild UCL sprain in his elbow. It wasn’t until September that he returned to the mound in a major-league game, and he was really only working a couple innings each time.
His total 2023 looked like this:
- 10 G, 6 GS, 33.1 IP, 3.78 ERA, 3.18 xERA, 3.47 FIP, 4.77 xFIP, 4.34 SIERA, 27.3 K%, 11.5 BB%, 0.54 HR/9, 1.20 WHIP
- 92 ERA-, 84 FIP-, 111 xFIP- (100 being league’s average for all 3 statistics)
- 32.9 Hard-Hit%, 3.7 Barrel%
- 112 Stuff+ (quantifies physical characteristics of pitcher’s pitches–release point, velocity, movement, spin rate, etc–and excludes results of pitches)
As a hard-throwing, young pitcher, these numbers aren’t terrible to look at. His ERA was 8 percentage points better than league average (92 ERA-) and his FIP was 16 points better (84 FIP-). A 32.9 Hard-Hit% (batted ball’s exit velocity = 95+ mph) was in the top 15% of the MLB among pitchers who threw at least 30 innings. His 3.7 Barrel% (in simple terms: a batted ball with the perfect combination of exit velocity and launch angle) was in the top 6% of the same group.
He would remain in a relief role going into 2024, and would quickly lock up the closer role for Oakland. Mason Miller’s breakout season had arrived:
- 55 G, 65.0 IP, 2.49 ERA, 1.77 xERA, 2.18 FIP, 2.21 xFIP, 1.91 SIERA, 41.8 K%, 8.4 BB%, 0.83 HR/9, 0.88 WHIP
- 64 ERA-, 54 FIP-, 53 xFIP-
- 30 Shutdowns (Win Probability Added 0.06), 5 Meltdowns (WPA 0.06)
- 32.5% Hard Hit%, 5.7% Barrel%
- 129 Stuff+
Miller’s average fastball velo shot up to 100.9 mph (100th percentile!) and was also number one in xERA (a 1:1 translation of xwOBA to ERA scale), xBA (Expected Batting Average), Whiff% (batter swing + miss rate) and K% (strikeout rate). His 37.4 chase rate–the number of pitches batters swung at outside of the strike zone–was 99th percentile.
It was a truly dominant campaign–the only problem was he played for an Oakland A’s team that finished an inspiring 69-93, held a -121 run differential (RD) and lagged 17 games out of the wild card race.
This all brings us to the current day–2025. The Trade Deadline has passed as of July 31, and Mason Miller, having a worse season than last (still very much special), has been dealt to the San Diego Padres.
FanGraphs reports his numbers as of August 6, 2025:
- 40 G, 40.1 IP, 4.02 ERA, 3.15 xERA, 3.14 FIP, 2.90 xFIP, 2.52 SIERA, 38.8 K%, 11.9 BB%, 1.12 HR/9, 1.07 WHIP
- 97 ERA-, 74 FIP-, 69 xFIP-
- 18 Shutdowns, 6 Meltdowns
- 42.3% Hard Hit%, 11.5% Barrel%
- 123 Stuff+
He’s had a couple of blowup games here and there, and actually gave up a 439-foot big shot to Lourdes Gurriel Jr. that came out of Miller’s hand at 103.9 mph and set the record for hardest pitch thrown that resulted in a home run. That’s not normal. What is normal is just how dangerous Mason Miller is on the mound and how dominant he can be for the San Diego Padres.
What he can do
There’s perhaps no one scarier to be facing on the mound in the later innings of a game. Standing 6 feet, 5 inches on an elevated mound makes Mason Miller’s imposing physique even deadlier–and that’s before he even throws a pitch.
He’s more than his body–and you’ll learn that quickly. This season, Miller’s in the 99th percentile in whiff rate and the 98th percentile in chase rate. Fastball. Slider. That’s what you’re gonna get and you can sit on that if you wish, but it’s unlikely you’ll catch up to the heater (unless you’re Gurriel) or recognize the offspeed in time to make good contact. Miller makes guys miss the ball completely at a better rate than Steph Curry has made 3-point shots in his career–and Steph Curry is pretty good at making 3-point shots.
His walk rate is up this year (11.9 BB%), but he is the number one strikeout pitcher in the league in terms of K-rate (38.8%). He’s abandoned his changeup in recent years, opting to use the fastball-slider combo, and while his -3 fastball run value has been bad this year (24th percentile), he’s made up for it with a slider in the 96th percentile in terms of run value (9). Both of those run values are according to Baseball Savant.
Savant also shows he’s steadily increased his slider usage from 24.5% in 2023 to 35.0% in 2024 to 43.5% in 2025. His slider boasts numbers like this:
- .132 BA (.163 xBA), .132 SLG (.218 xSLG) , .144 wOBA (.187 xwOBA), 48.9 Whiff%
That ranks 13th in batting average against, 3rd in slug against, 6th in wOBA against and 9th in swing-and-miss rate.
With Miller, San Diego is adding a deadly combination of heat and deception to a bullpen that was already one of the best in the MLB.
Where he fits in the Padres ‘pen
As of August 6, 2025, the Padres hold the best bullpen ERA and FIP in the majors: 3.02 and 3.49, respectively.
Robert Suarez holds the closer position, although it’s likely that multiple pitchers will take that role from time to time, depending on usage and fatigue. Nonetheless, Suarez boasts 3.17 ERA and 2.55 FIP, while others like RHP Jason Adam (1.82 ERA, 3.20 FIP), LHP Adrian Morejon (2.13 ERA, 1.95 FIP), RHP Jeremiah Estrada (2.61 ERA, 2.71 FIP) and LHP Wandy Peralta (3.10 ERA, 3.55 FIP) all have thrown at least 50 innings and been extremely effective.
Miller will slot into a setup/close-when-needed role and give the Padres even more room for comfort if their starters do not last further into games. Any combination of those aforementioned relievers give San Diego a significant advantage over other clubs’ bullpens. Miller should even be counted on for multi-inning work, considering he began as a starting pitcher.
Miller’s Future
4 years of team control after 2025 gives the Padres a couple of avenues to consider.
One of those avenues is locking Miller up ASAP. What they can do is sign him for at least his remaining arbitration years to guarantee a (likely discounted) price tag on his salary. The other direction to think about is to play it out year by year, avoiding any sort of long-term commitment on a bullpen arm.
Now I’m not saying it’s smarter to go either direction, but they did give up a prospect haul, including one of the best prospects in the entire sport, to land this guy. I would say that they are very confident in his current abilities, as well as the prognosis of his career.
Miller is 26, and he wouldn’t hit the open market until he’s 32. The Padres could have arguably the best relief pitcher in the game for a fraction of the cost of an Edwin Díaz of the Mets or a Josh Hader of the Astros. Díaz is on a 5 year/$102M deal ($20.4M AAV) with an opt-out after this season and a 2028 club option and Hader is on a 5 year/$95M contract ($19M AAV) that he signed in 2024. Both of these closers were on the open market, so they weren’t in the same negotiating situation as Mason Miller.
With Miller, the Padres could look to offer something closer to Emmanuel Clase’s or Andres Muñoz’s contract (perhaps Clase should’ve signed for more money). Clase signed after a year of ML service time at 5 years/$20M ($4M AAV) with two club options in ‘27 and ‘28. Muñoz signed for 4 years/$7.5M ($1.875M AAV) with $6M, $8M and $10M club options in ‘26, ‘27 and ‘28, respectively. Both bought out their arbitration years early on and therefore had lower AAVs with club options later on. Miller is older, has more service time and has more of a track record than those two did at the time of their signings to warrant a bit more.
AJ Preller is no stranger to giving relievers big contracts. Robert Suarez signed a 5 year/$46M ($9.2M AAV) deal with Preller in 2023. Yuki Matsui (5 year/$28M) and Wandy Peralta (4 year/$16.5M) both inked their agreements in 2024–the former an international free agent.
It’s no secret the Padres made a splash with acquiring the golden arm of Mason Miller. If he lives up to expectations and helps San Diego win a World Series, the prospect capital Preller dealt away will be easily forgotten. With Miller, the club is putting themselves in the best possible position to get that done.
Give me your opinions
- Is Mason Miller worth the prospect package given up?
- What do you think is the better path for the Padres in terms of Miller’s future contract?
Inner Half 