Alek Thomas Has Made Tremendous Strides Backwards (and That’s a Good Thing)

When I began writing this piece about Alek Thomas‘ defense, it was in response to the excellence he had shown in the postseason as Arizona’s everyday centerfielder. Since then, an elephant walked into the room in the form of his ninth-inning error in Game 5 of the World Series, and while it didn’t cost the Diamondbacks the title or even the game, it undoubtedly left a bitter taste in his mouth that he’ll likely spend much of the offseason trying to rinse out. But his late-game error was a tragically timed blip on an otherwise excellent performance this October — one that speaks to the specific improvements he’s made to his outfield defense, and how those adjustments have altered his forecast as a big leaguer. So let’s take a look at how Thomas’ defense has evolved since his days as a bat-first prospect, rewinding to this catch in Monday night’s Game 3.

That catch was one of several he made throughout the postseason, which provided Thomas with a national audience to wow with his range in the outfield. The way he covered ground out there played well on TV, too, particularly how he went back on deep balls to center field, sprinting with his head down toward the wall and making mid-route adjustments as needed. But while his wall-banging robbery of what would otherwise have been an RBI double for Mitch Garver was an obvious defensive highlight in its own right, it was also a clear indication of the improvements Thomas has made to his center field defense over the past couple seasons.

Before his arrival in the Arizona outfield, Thomas was a standout prospect. He spent his time in the minors climbing our rankings, ultimately claiming the No. 2 spot on the D-Backs list behind fellow speedy outfield phenom Corbin Carroll and ascending from the 70s to the 20s on our annual Top 100 lists. His bat was what got him there; Thomas boasted one of the more dynamic swings in his prospect class, and his athleticism at the plate was seen at the time as making up for outfield defense with obvious flaws. That defense relied heavily on his speed to make up for sub-par arm strength. At the time, his role in center field was seen as little more than a stopgap, filling in until Carroll was deemed big-league ready, with the idea that Carroll’s eventual promotion would result in Thomas’ relocation to a corner.

Of particular concern was Thomas’ ability to track deep fly balls hit directly over his head. “His speed allows him to glide from gap to gap with ease,” we wrote in our 2022 Top 100 write-up, “but Thomas looks much less comfortable going back on balls straight over his head.” Like most outfielders, he is at his best when he’s able to plant himself under a fly ball rather than catch it on the run, and he’s so fast that he’s able to do that on a wide radius of balls that other, less speedy outfielders might have to dive for. But in the minors and in his early days as a big-leaguer in 2022, he would be so focused on using his speed to get in position that he would lose sight of the ball, failing to account for the slicing shape of its path, and would wind up out of line with its trajectory without sufficient time to correct his course, resulting in iffy, on-the-run jabs at the ball with his glove. Other times, he’d get to the wall, only to time his jump poorly or fail to get his glove up in time, resulting in the ball caroming off the wall or, in several instances, his body.

But over the course of the 2022 season, Thomas steadily improved on these flaws. He got accustomed to the Arizona outfield and made a habit of keeping a better eye on the ball when it was in flight over his head, even when sprinting directly backward. This also seemed to afford him a better sense for which balls off the wall were worth jumping after and which were better to play on the rebound. By the following spring, Thomas had graduated out of prospect-dom, but it was Carroll who was now expected to relocate an outfield corner, thanks to Thomas’ ability to hold down the fort in center (Carroll’s offensive thump didn’t hurt matters either).

Thomas continued to improve on getting back on the ball in 2023 — so much, in fact, that on Baseball Savant’s Outfield Directional Outs Above Average Leaderboard, he ranks third among all qualified outfielders on balls for which he had to range straight back, and first among center fielders in that category. Sure, it’s a granular skillset to home in on, but given that it was one that was specifically called out in his prospect report and he’s now among the top ranked at the top level, it’s at least worth a quick hat-tip to the young speedster.

The proverbial cap-doffing isn’t the only thing that Thomas’ defensive improvements have earned him. For one thing, establishing himself as a reliable up-the-middle guy alleviates the pressure that would be applied to his meager power production were he to move to a corner outfield spot. For another, he’s demonstrated an ability to improve at the big league level, which is particularly impressive given that he’s still just 23 years old. And for what it’s worth, he was able to maintain it during the postseason, making several catches in deep center field on these types of fly balls.

There’s still plenty of room for improvement. Thomas’ arm remains a relative weak point, and his glovework could use shoring up, as evidenced not only by his Game 5 gaffe, but also by a ball squibbing out of his glove on a sliding stop in Game 4 as well. He still relies heavily on his speed, and while he’s gotten better at tracking and snagging deep fly balls, his plays often lack the fluid sure-handedness that we associate with elite outfielders. His routes have improved to the point where he’ll get himself in position accordingly, but unless he has time to station himself under the ball, his hands still seem clunky and haphazard, even when he does come up with the ball. Even after some of his more impressive catches, it wasn’t uncommon to see him glance wide-eyed into his glove as though he wasn’t sure it worked, as was the case with his Game 3 catch against the wall. In other words: he doesn’t always make it look easy out there.

But it’s not easy! It shouldn’t look easy! It’s true that when we think about truly stellar outfield defense, “clunky” isn’t a word that comes to mind. But given the defensive strides Thomas has made, both literal and figurative, since his big league debut, he’s earned our patience as we wait out further focused improvement.