Baseball is back and with spring training ramping up, Philadelphia Phillies fans will be looking for a few specific faces at training camp this year. One of those faces is star prospect Aidan Miller, who has suddenly catapulted to the front of the pack. Now that Miller is ranked as the Phillies' top prospect there will be even more hype building up toward his eventual MLB debut.
That debut could come as early as later this season. When Miller does finally make it to Citizens Bank Park, fans are in for a treat thanks to his top-end projectable bat.
There's something also going to be something very familiar about Miller's approach at the plate. It's something that will remind Phillies fans of another former top prospect: Bryce Harper.
Phillies' star prospect Aidan Miller and former MVP Bryce Harper both love crushing fastballs
MLB.com's David Adler recently shared an eyebrow-raising (in the good way) Statcast stat about the 21-year-old shortstop. Miller absolutely punishes fastballs. Adler notes that the data from the past two seasons doesn't include Miller's time in Double-A (no Statcast capability) but a large sample size from Single-A and some from Triple-A last season.
Against all fastball types, Miller has hit a beefy .373 with a .591 slugging percentage.
That's right. And here's the damage he's done against individual fastball types:
Pitch | BA | SLG |
|---|---|---|
Four-seamer | .397 | .571 |
Sinker | .353 | .588 |
Cutter | .308 | .692 |
All fastballs | .373 | .591 |
Adler also notes that Miller has had success against fastballs with MLB velocities, batting .357 and slugging .714 against heaters 95 mph or faster.
How does this relate to Harper? Even though the general narrative is that the two-time NL MVP had a "down" season in 2025, one of the things we learned is that MLB pitchers are just not throwing him pitches to hit, especially fastballs. And there's good reason.
Harper absolutely destroys fastballs and has been doing so pretty much his entire career. He has slugged over .500 against fastballs in all but one season of his MLB career (.479 in 2016). His career slugging percentage against all fastballs is .588.
Aidan Miller still has plenty to work on before any other Bryce Harper comparisons
Now, are we saying that Miller will be what Harper was when he debuted with the Washington Nationals? No, that would be a stretch. Harper was a generational talent and his arrival in the big leagues was nationally anticipated.
But having something, anything in common with a future Hall of Famer can't be a bad thing, right?
It's no mistake that Miller's spring locker is situated next to Harper's, hopefully more of his traits rub off on what the Phillies hope will be their next big bat.
Miller will have his struggles when he finally reaches the majors. It's the exception when a prospect doesn't have a steep MLB learning curve. One area he'll have to show some improvement on this season in Triple-A is against breaking and offspeed pitches, which Adler also points out.
In his very small eight-game sample from Triple-A last season, in which Miller slashed an impressive .333/.514/.519, he floundered against breaking balls. Against sliders he had a .035 xBA and .039 xSLG. Against sweepers he fared a little better, with a .184 xBA and .269 xSLG, but you can see that there's plenty of room for improvement.
Miller is by no means a finished product, but the Phillies and the scouting community in general are very high on the youngster. Whether he ends up at third base or second remains to be seen, but eventually he'll hit in the majors, stacked in the Phillies' lineup alongside Harper.