Corbin Carroll Has Powered Up

Corbin Carroll had one hell of a 2023. Even before he was unanimously voted NL Rookie of the Year on the strength of a 25-homer, 54-steal season, he landed an eight-year, $111 million extension. He capped his stellar season by helping the 84-win Diamondbacks through a memorable, improbable October run to their first World Series appearance in 22 years. Yet for the first half of 2024, the D-backs’ dynamo rarely played up to last year’s standard, while his team struggled to stay within sight of .500. Since the All-Star break, it’s been a different story, as Carroll has rediscovered his stroke while spurring the red-hot Diamondbacks into Wild Card position.

The short version of the story is that Carroll hit just .212/.301/.334 (79 wRC+) through the first half, homering just five times; he didn’t hit his third shot until July 7. The Diamondbacks slipped below .500 on April 17 and didn’t get their heads back above water until July 12, in the midst of a four-game winning streak that helped push them to 49-48 at the break. They haven’t looked back, going 30-13 in the second half, the majors’ second-best record behind the Padres (30-12), and at 79-61, they’re now half a game out of the NL Wild Card lead, with playoff odds of 88.6%. Carroll has hit .282/.356/.647 (166 wRC+) with 14 homers since the All-Star break; his 11 homers in August was one shy of the majors-leading 12 hit by Aaron Judge and Shohei Ohtani. His hot streak has helped the Diamondbacks weather the absences of both Christian Walker (who missed all of August with an oblique strain) and Ketel Marte (who’s been out since August 19 with a left ankle sprain).

The longer version of the story is that the 24-year-old Carroll’s resurgence has allayed concerns that stretch back to the middle of last season. Overall, he hit .285/.362/.506 (132 wRC+) while making the NL All-Star team, finishing eighth in the league in WAR (5.4) and fifth in the MVP voting. Yet even within that stellar campaign, he experienced a notable drop-off in performance. Carroll hit .290/.366/.559 (146 wRC+) with 17 homers through the end of June but slipped to .280/.356/.452 (118 wRC+) with eight homers from July onward; the dividing line for those two almost exactly equal stretches (323 plate appearances for the former, 322 for the latter) was his departure from a June 29 game due to soreness in his surgically repaired right (non-throwing) shoulder. He tore his labrum and posterior capsule in 2021, which cost him nearly the entire season.

In the wake of his removal from that game, Carroll underwent strength testing, which showed that his shoulder was strong and stable, but the Diamondbacks gave him a breather, limiting him to a single pitch-hitting appearance over the next three days. On July 7, after his return to the lineup, he again took an early exit due to shoulder pain. “I took a swing, and I felt a shift in my shoulder, shocking, tingling sensation go down my arm and then my hand go numb,” he told reporters. “I was just holding it thinking it came out of the socket, pretty much thought that the season was over.”

Fortunately, Carroll was again fine and returned to the lineup the next day. Though he didn’t hit the ball quite as hard over the remainder of the season, he was still productive, as noted. He had several big moments throughout the postseason, though he slugged just .259 after homering twice in Arizona’s first three playoff games (the openers of the Wild Card and Division Series).

This season, Carroll stumbled out of the gate, batting just .193/.292/.246 (58 wRC+) in April and .202/.270/.343 (68 wRC+) in May. While his history of shoulder problems offered a potential explanation, neither he nor the team publicly cited that as the reason for his troubles. Instead, in late April, Carroll explained that while making small tweaks to his swing over the winter in order to improve his bat speed and better handle fastballs and cutters, he inadvertently made his bat path too flat. A few weeks later, as his performance improved a bit, he drew a more explicit link between his mechanics and his performance, telling Fox Sports’ Jordan Shusterman, “I was popping a lot of balls up, and like, counterintuitively, it was because my swing was too flat… My window for success was small. I was either on top of balls and hitting groundballs, or I’m under the ball and it’s popping straight up.” More:

From watching video early in the season, Carroll identified that he had been “counter-rotating” too much while loading his swing. In other words, he was turning more inward toward the catcher before firing the bat into the zone rather than starting from a more balanced, upright base and attacking the ball at a more vertical angle.

The counter-rotation caused Carroll’s bat to enter the zone at too flat an angle, and messed with his timing as well as his quality of contact. “The more we turn back to the catcher, the more we gotta open up,” Diamondbacks hitting coach Joe Mather told Shusterman. “We gotta make earlier decisions. All kinds of things can happen with that — velocity becomes more of a challenge. That was something that he was feeling.”

Having identified his mechanical woes, Carroll worked to fix them. While he didn’t recover his power initially — and slugged just .380 over the calendar year from July 1, 2023 to June 20, 2024 — it finally showed up in a big way. His performance has improved in every full calendar month, while his penchant for popups has dwindled:

One aspect of his season that’s worth noting is that Carroll spent most of the first three months playing center field while Alek Thomas was sidelined by a left hamstring strain. Through June, Carroll started in center 72 times, compared to five in right field, but since the start of July he’s made just one start in center (July 3), and 47 in right; Thomas returned on July 2 and initially shared the center field job with Jake McCarthy before being sent down on August 14, leaving McCarthy as the full-timer. By the metrics, Carroll isn’t as strong a center fielder as a right fielder, so it’s fair to wonder whether the additional physical and mental demands of the middle pasture contributed to those early-season woes.

Back to the batting. We don’t have public bat speed metrics for 2023, but Shusterman reported that the Diamondbacks assured Carroll that his bat speed had improved relative to last year. With the new-for-2024 data, we’ve learned that he has 77th-percentile bat speed overall, with a 73.7 mph swing that’s shown relatively little variation across the two stretches of this season that are under discussion; his rate of squared-up pitches has improved (from 26.9% of swings to 31.9%), as has his blast rate (from 14.3% to 15.1%). The public Statcast data doesn’t include vertical bat angle (VBA), but the proprietary SwingGraphs site did show Carroll adjusting towards his 2023 swing as of about a month ago:

As for the public data, Carroll’s trend towards improvement isn’t quite as smooth when it comes to his Statcast contact numbers, but he has generally hit the ball harder with each passing month, and much harder since the start of July than before it:

Those last two lines — showing a nearly 4 mph increase in exit velocity, a barrel rate that’s more than doubled and a slugging percentage that’s nearly done the same — are like comparing night and day; from the first stretch to the second, his wRC+ basically doubled, from 76 to 150. In fact, Carroll’s numbers since the start of July are better than his overall ones from 2023 (90.0 mph average exit velo, 7.6% barrel rate, 40.9% hard-hit rate, .441 xSLG, .344 xwOBA), though again, that set is a byproduct of two very different stretches, and this latest stretch is the smallest sample by nearly 90 PA.

Looking at his splits by pitch type, and again using that June 30/July 1 dividing line, Carroll is still struggling against four-seam fastballs, though not to as great a degree as before, and his improvement pretty much runs across the board:

Against the seven pitch types he’s seen most often (accounting for just under 90% of his total pitches), his average exit velocity, SLG, xSLG, and wOBA have all increased, and in terms of his xwOBA, his performance against everything but sliders and cutters has improved; against those two, he’s declined, but only by a few points. I didn’t fit it into the table, but with the exception of sliders, his whiff rates haven’t changed by much. Against four-seamers, his rate has increased from 17.5% to 18%, while against curves it’s dropped from 26.7% to 24.1%; as for those sliders, it’s risen from 22.6% to 33.9%. His overall strikeout rate has increased from 17.5% to 19%, hardly a concern given the steep increase in overall production.

Speaking of rising, Carroll absolutely punished high four-seamers — those in Gameday zones 1, 2, 3, 11, and 12 — in the first few months of 2023, but he’s struggled mightily against them since, though his ’24 numbers show a modest in-season improvement:

All of which is a reminder that Carroll may not be all the way back to last year’s level, whatever that is. As with so many streaks and slumps, the truth probably lies somewhere between the extremes he’s exhibited. The good news is that he’s playing at a star level again, and that his supporting cast has risen to the occasion, as nine of the other 10 Diamondbacks with at least 60 PA since the All-Star break have hit for a 119 wRC+ or better, helping to cover for a pitching staff that’s still a work in progress. Chances are, we’ll be seeing them again in October.