Double-A Notebook: Takeaways on Phillies Prospect Aidan Miller

Throughout this season, I’ve been doing a series of stories breaking down the top players and most interesting prospects I saw come through the Altoona Curve, my hometown minor-league affiliate. In those stories, there were plenty of prospects to go over, ranging from the first overall pick in last year’s draft to other big-time first-round picks.

A few weeks ago, I had the pleasure of watching another one of our top 100 prospects up close, as the Phillies’ top prospect, Aidan Miller, came to town with the Philadelphia Phillies’ Double-A affiliate. Out of all the prospects I’ve seen up close this season, I can confidently say Miller was one of the most impressive players I’ve watched to this point.

Miller, Just Baseball’s No. 52 overall prospect, was the only member of the Reading Fightin’ Phills that stood out to me, as his performance came second to none. The Altoona Curve have put together a very solid pitching staff this season, and Miller handled their most difficult arms with ease. Miller also stood out above Konnor Griffin in a few games during the series, which isn’t an easy thing to do.

Without further ado, let’s dive into some of the main things that stood out to me about Miller’s performance in Altoona, his numbers, and the high big-league ceiling he potentially possesses.

Taking a Look at His Production

To put it simply, Miller tore the cover off the baseball during his time in Altoona. I managed to see him in the middle of one of the strongest stretches of his career, as Miller was red hot in August. In fact, he played so well during this month that he actually managed to salvage his numbers on the season, which weren’t too impressive after a slow start to his 2025 campaign.

During the six games Miller played in Altoona, he slashed .522/.621/1.000 with a 339 wRC+. In this same span, Miller recorded seven extra-base hits, which included five doubles and two home runs. For good measure, he also drew four walks, drove in seven runs, and stole two bases during this stretch as well.

When thinking back to the 69 home games the Curve played this season, I truly can’t think of a better stretch of games from a player. It genuinely felt like the Altoona Curve’s pitching staff couldn’t get him out, and when they did, it was a huge accomplishment.

Miller’s two home runs both came on the same night, as he notched one of the most impressive single-game performances I’ve seen all season long. Both of these blasts traveled over 420 feet at 108 and 109 mph off the bat, making them two majestic blasts.

Miller had two games during the week where he recorded multiple extra-base hits, as well as three separate games where he notched three hits. It seemed like when Miller did damage, he made it count, killing every pitch thrown his way in each of these games.

It’s hard to explain just how impressive this stretch of success truly is, as Miller was one of the toughest hitters to navigate I’ve seen all year long.

Things That Stood Out About Miller’s Game

Now that we’ve covered the numbers behind Miller’s impressive six-game stretch against the Curve, we can take a closer look at some of the other things that stood out to me when watching him play.

First of all, when he gets ahold of the ball, he produces some of the most electric power I’ve seen from a player in Double-A. As I previously mentioned, he hit two home runs over 420 feet at 108 mph or better, which really speaks to this electric power.

His furthest blast traveled 435 feet, landing in the grass beyond the outfield bleachers in left field. For those who are unfamiliar with People’s Natural Gas Field, this area of the ballpark has only been reached by some of the most prolific power threats to come through Altoona.

Despite having this significant power in his bat, Miller remained relatively patient and disciplined at the plate. He drew four walks in comparison to five strikeouts, as he wasn’t afraid to patiently await his pitch. Even when Miller went down on strikes, he rarely chased or looked overpowered, which is a very positive indicator for someone his age.

This ability to not expand the zone will be incredibly important moving forward, as he’ll be able to force opposing pitchers to throw him more in-zone heaters, which he crushed. If he can truly maximize the power he showed at the plate, he could become a lethal power threat once he is in the big leagues.

With his power also came incredible bat speed, as he was able to whip the barrel through the strike zone faster than most hitters I’ve seen this season. This helped him handle the occasional high velocity he saw from the Curve’s pitching staff, which contributed to him rarely being beaten at the dish.

Although his bat speed looked very impressive, he didn’t sacrifice his barrel control in the process. In fact, of all the things that stood out when watching Miller, his barrel control is what caught my attention the most.

No matter how quick his swing was, he consistently squared up pitches and kept the barrel in the zone long enough to cover different pitch types and locations. That kind of barrel control is rare for a hitter his age, and it allows him to consistently slug extra-base hits.

Knowing this, it makes sense that Miller managed to record 40 extra-base hits this season, an impressive mark considering just how slow of a start he got off to earlier this year.

Although I’ve spent a lot of time talking about his bat — and deservingly so — his speed is also one of the most underrated pieces of his game. Despite going just 2-for-4 on stolen base attempts during that series, he flew across the basepaths. I really didn’t expect this type of speed out of Miller either, so I was slightly caught off guard.

Shortly after he was in Altoona, Miller stole his 50th base of the season, something a member of the Reading Fightin’ Phills hasn’t done since 1987, which really speaks to how fast he truly is.

Miller also remained smooth in the field, as he rarely looked challenged at shortstop. Even when he was faced with hard-hit ground balls or weird hops, he handled them with ease, making difficult plays look routine.

Miller showed a very polished game during this stretch in Altoona. The power was more impressive than advertised, the approach was advanced beyond his years, and the athleticism he flashed on the basepaths and in the field proved he’s far more than just a bat-first shortstop.

How High Is Miller’s Ceiling?

After taking some time to reflect on what I saw in Miller’s week in Altoona, I was left wondering: How high is Miller’s future ceiling?

Comparing Miller’s game to other players I’ve seen this year, I can confidently say he was one of the most well-rounded and talented players I’ve had the pleasure to watch. He flashed five tools, which will allow him to be more versatile and valuable with his playstyle than a few other impressive prospects I’ve seen this season.

Miller will be a very good runner, a plus defensive shortstop, and a serious threat in the batter’s box. Knowing this, the sky is the limit for his future potential. Once he figured out Double-A pitching, he was nearly unstoppable, which also shows the ability to overcome failure, something that’ll be huge once in the big leagues.

When you combine his advanced approach with the raw tools he already possesses, it’s hard not to envision Miller developing into a cornerstone big leaguer. His ability to impact the game in so many ways gives him one of the highest ceilings of any prospect I’ve seen this season, and if he keeps developing at this rate, he has a real chance to become a star at the next level.

Miller was just promoted to Triple-A following play on September 7, and this will be one of the most important challenges he’ll face. If he handles this with grace, I’ll have even more faith in his future as a cornerstone big leaguer.