How the Diamondbacks' Alek Thomas broke down his swing and put it back together
To begin his first swing of spring training, Alek Thomas planted his right foot in the batters’ box, stepping directly towards the pitcher’s mound. He fired his hips, then his shoulders, then his hands. He did not roll over onto his heel, or yank his body towards first base. He stayed on an inside cutter, the type of pitch that has foiled him for two seasons, and lined a 103.2 mph base hit into right field.
The differences were subtle, but they were real. This was Thomas’ new swing — or to be more accurate, a conscious return to his old swing — in action. It was the first real, tangible result from an off-season of deconstructing everything and starting over. It was, the Diamondbacks hope, the key to unlocking a crucial piece of their present and future.
This is a player who, just over four months ago, hit the biggest home run in Diamondbacks’ history. That’s not a matter of opinion. By Baseball Reference’s championship win probability added, Thomas’ shot to tie Game 4 of the NLCS increased the Diamondbacks’ chances of winning the World Series by 6.69%, the largest gain from any home run ever hit by an Arizona player.
It would have been easy for Thomas to rest on the laurels of that hit, and to assume he had solved his struggles. In the playoffs, he had a .734 OPS, a healthy number when combined with his elite defense in center field. But Thomas saw those bright spots differently. They were evidence of what he can be at his best.
“That moment that I had, those home runs that I had, I felt like I was just in a good position right there,” Thomas said. “But all the other at-bats that I had during that playoff stretch, I felt like I wasn't in the best position.”
Thomas now has 755 regular season at-bats bats across two seasons in the major leagues. His number paints a clear picture of who he has been. His batting averages in 2022 and 2023, respectively, were .231 and .230. His OPS+ has been 75 in both years, placing him 25% below the league average hitter. By wins above replacement, he’s fallen between 0.5 and 1.5, depending on your preferred methodology. The simple summary: He has not consistently been the type of impact player that he was projected to be as a top prospect two years ago.
“I feel like I have more to give to the team,” Thomas said. “.230 is not me and I've done that for the past two years.”
So this off-season, Thomas set out to change that.
The benefit for Thomas lies in his background. His dad, Allen, was a strength and conditioning coach with the White Sox for 28 years and has been Thomas’ personal hitting coach since he could walk. Shortly after Thomas first debuted with the Diamondbacks in 2022, Allen knew that something was wrong with his swing. After impressing with a .788 OPS through 41 major league games that summer, he had a .517 OPS over his final 72 games.
But identifying a problem and fixing it are two separate puzzles. And in 2022, Allen wasn’t sure how to do the latter.
“I didn't have the resources,” Allen said.
That changed last spring, when he partnered with a trainer named Chad Miller to open ID Evolution, a new hitting training company based out of the East Valley.
Miller’s background is in the science of hitting. Equipped with the technology to break swings down to the millisecond and millimeter, the pair was able to view Thomas’ swing in more detail than ever before.
Around the same time that Miller and Allen Thomas began their partnership, Alek Thomas played with Mexico in the World Baseball Classic. Even then, before the season had started, Allen could see that his son’s swing was still broken — a far cry from the hitter who had dominated the minor leagues and shot up prospect rankings before his debut in 2022.
“He showed spurts of getting back to his normal self,” Allen said. “But then (the issues) would come back.”
Specifically, the problem was this: Thomas would load his weight awkwardly over the outside of his back foot. He would then step towards home plate, rather than directly back at the pitcher. From that closed position, he had to pull his upper body awkwardly towards first base to reach inside pitches.
“Balance begets direction, direction begets timing,” Miller said. “And Alek is truly that equation in living, breathing form.”
Miller could see that from tracking technology, which showed that there was minimal time elapsing between Thomas activating his hips, shoulders and hands. That time is known as separation, and it’s crucial for generating force.
To create that separation, Miller broke Thomas’ swing into its core components. Every day during the two months that they worked together this winter, Miller had Thomas work on each individual portion of the swing separately, training him to not rotate his entire body at once. Then, when Thomas put the swing together, separation could come more naturally. At the same time, he addressed the balance and direction issues, landing with his weight spread throughout his front foot, rather than on his heel.
There’s a balance here, between letting Thomas unleash his natural swing and wanting his mechanics to work. He still rolls onto the outside of his front foot and opens his body more than many hitters. But to Diamondbacks’ hitting coach Joe Mather, the key word is “control.” And now, he believes Thomas is under control.
“Just try to eliminate rolling over as much as possible,” Thomas said. “Cause I did that a lot the past two years and I just want to get back to my normal self and drive the ball to all fields.”
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All of it is stuff Thomas has done before, when he was in the minor leagues.
“We're just getting back to who Alek Thomas really was,” Allen said.
The Diamondbacks had tried to make these changes in bits and pieces over the past two seasons, but there’s a balance with putting too much on the plate of a young player. Plus, deconstructing a swing mid-season is a losing proposition.
“You should get worse before you get better if you're changing something,” as Miller explains.
By making a conscious effort to fully deconstruct and reconstruct Thomas’ swing, the goal is that he’ll not only get back to his old habits, but understand those habits well enough to maintain them.
“He couldn't feel it,” Allen said. “So when he saw it, he was like, ‘Ah man, I am rotational. There is no difference in my hands and my shoulders moving at different times.’ So that was a big light bulb.”
At the onset of spring training games, before wrist soreness sidelined him for a week, Thomas said that feeling fully natural in his retooled swing remains a work in progress. He’s to the point where he’s not thinking about his mechanics in games, but it remains part of his thought process in the batting cages.
“It's like 80/20,” Thomas said. “But that 20% feels like a little bit more because of how much time and effort I've put into making sure that I've corrected it.”
In the meantime, the results he’s seen have been encouraging. In tracking sessions with Miller at the beginning of the off-season, Thomas had less than 10 degrees of separation between his hips and shoulders at the time of contact. By the end of the off-season, that number was over 20 degrees. The difference showed in live batting practice sessions over the winter. In his two major league seasons, Thomas has never hit a ball harder than 111.3 mph. In an at-bat against a Triple-A pitcher before spring training, he hit one 116 mph.
“I'm like, ‘No way,’” Thomas remembered thinking. “I don't hit 116.”
Doing so in a real game, against major league pitching, is a different proposition. But if there’s one thing the postseason run did give Thomas, it was confidence.
“I feel a lot more relaxed and calm,” Thomas said. “Cause I was on the biggest stage, I was in the World Series.”
He was in the World Series, but he also hit just .238 in those five games. Armed with a new version of his old swing, he hopes those type of numbers stay in the past.
This article originally appeared on Arizona Republic: Off-season swing changes have Alek Thomas aiming for new heights
