Alek Thomas vs. other notable young AA phenom prospects

As you can already tell from my Minor League Recaps, there is now an Alek Thomas segment every day. Thomas is off to a blistering start with the Diamondbacks AA affiliate in Amarillo, putting up an obscene .343/.434/.600 slash line with 6 doubles, 3 triples, 2 homers, and a 12/17 walk to strikeout ratio in his first 83 plate appearances. All in all, that puts his park adjusted weighted run creation (wRC+) value at 184. For Thomas, who turned 21 just days before the season started, that is absurd and worth taking a deeper dive into.

For comparison, here are some of the best performances at the AA level in recent memory with the players sorted by age.

There is a lot of quality players on this list, but the one pattern that persists is the great players produced a wRC+ north of 175, with Mookie Betts and Brandon Belt producing the lowest number of the All-Star players at 177. Thomas is currently sitting in that range, so we’re hoping he can keep it up. If there is one concern I do have, I don’t think his power numbers will stay good enough to keep his wRC+ up into that elite range. I think ultimately he’s going to fall short, but you’re still likely to get a very good player nonetheless. While perhaps not an MVP candidate or offensive powerhouse, his defensive projection in the outfield combined with plus speed and feel for hit will make him a worthwhile MLB player for a long time and get a couple All-Star nods along the way.

For those that don’t know about Thomas’ history in Arizona, he is the son of current White Sox strength and conditioning coach Allen Thomas. He’s grown up near an MLB clubhouse, so he has a pretty decent idea of the professional baseball player lifestyle and what it takes to succeed. The Diamondbacks took him with the 62nd overall selection (2nd round) of the 2018 MLB Draft and signed him for $1.2M. In the two years he’s had a chance to play in affiliated ball, Thomas has done nothing but hit. In a Spring Training game in 2019, Thomas skied a homer off White Sox ace Lucas Giolito with his old man watching from the opposite dugout.

In 402 PA in Low A, Thomas would produce a 153 wRC+ with the Kane County Cougars in the Midwest League. He scuffled a bit in a short sample in Visalia, but would cap off their season with a double that clinched a championship. He would spend 2020 training at the Alternate Site and was one of the best prospect performers there and in instructional league play in the fall. Going into 2021 he was a consensus Top 100 prospect, ranked #94 by Baseball America, #81 by MLB Pipeline (49 the year before), and #47 by Baseball Prospectus. Despite the cancelled Minor League season, the team opted to go for an aggressive promotion by placing Thomas with the team’s AA affiliate in Amarillo, TX.

If we were to extrapolate Thomas’ first 83 PA to about 250, you can pretty much just triple the counting numbers I put up above. Some things will regress, as his .423 average on balls in play is simply unsustainable even though there is evidence of a high BABIP skill from the young outfielder. We’ll likely see that number settle in the .360-.380 range he’s sat around at each level. As that number drops, we probably want to see that offset by a jump in ISO and have him hit more doubles, triples, and home runs. Overall he has 11 extra base hits in 83 plate appearances, which is a good ratio for a guy who’s more known for line drive contact than over the fence power.

What we do know with Thomas is his approach is consistently with a high BABIP skill due to high exit velocities and whole field approach and he has plenty of pull-side power. What will determine his ceiling is his ability to do damage to left and center field on pitches on the outside-third of the strike zone. We’ve also seen a complete change in the type of contact he produces as he’s gone from a ground ball hitter to a fairly even ground ball/fly ball splits in 2021. The ground ball rate has dropped from over 50% in 2019 to less than 40% in 2021 while seeing a jump in fly ball rate from While not hitting more fly balls out of the park, Thomas is hitting more fly balls and less ground balls, an indication of a future potential breakout or in Thomas’ case a breakthrough that has caught the organization’s attention.

With more air contact combined with the high exit velocities he generates at the plate, we could see a bit of a jump in his overall power numbers. Going into the season, I always thought he was an adjustment or two away from being a mid tier Top 100 prospect to an elite prospect who you can build around. That adjustment has been made so far, the question is how long can he keeps this up. In regards to when Thomas may get an opportunity at the MLB level, we can revisit this question at the end of July. By then we should have a sufficient enough sample size to determine if he is the answer to the team’s long time center field problem.