What's up with Corbin Carroll?

The Diamondbacks are an MLB-best 38-20 since June 1, surging into postseason position behind a white-hot offense. Arizona averages 5.14 runs per game — and 5.77 over the past nine weeks — to lead baseball. 

That’s not entirely surprising, considering Arizona added Eugenio Suarez, Joc Pederson and, more recently, Josh Bell to an NL Pennant-winning group from last season. What is surprising, though, is the success has largely come without Corbin Carroll – not because Carroll has been hurt, but simply because he has struggled so immensely.  

Last year, Carroll burst onto the scene as one of baseball’s preeminent young stars. He hit .285/.362/.506 with 65 XBH and 54 SB, winning Rookie of the Year honors and finishing fifth in National League MVP voting. As an encore, Carroll has hit .215/.307/.366, good for a mere 89 OPS+, which is to say his offensive production has been 11% worse than league average. 

When exploring such a steep one-year decline, I like to start by looking at the player’s batted-ball profile. But we don’t see much significant change in Carroll’s. 

Carroll’s Batted Ball Profile by Year	2023	2024
GB%	43.9%	45.1%
LD%	19%	17.3%
FB%	37.1%	37.6%

Let’s dive a little deeper. Carroll’s IFFB% -- his infield pop-up percentage – is 23.1%. Last year, his IFFB% was 11.7%, which aligns with the league average (11%). So while Carroll is hitting an equal percentage of fly balls, nearly a quarter of those are pop-ups, the worst batted ball for a hitter; essentially, a pop-up produces the net value of a strikeout. That explains Carroll’s steep drop-off in his production on fly balls. 

Carroll’s Production on Fly Balls by Year	2023	2024
wOBA	.420	.173
SLG	.803	.324

*League Average = .333 wOBA and .620 SLG

Few players are generating less production on fly balls than Carroll. Of 161 players with at least 75 plate appearances ending in a fly ball, Carroll’s wOBA ranks 157th. Even if we remove pop-ups, we still see several disconcerting trends. On average, Carroll’s non-pop up fly balls are being hit 1.5 mph less hard, traveling 19 fewer feet, and registering a launch angle three degrees steeper. Which is to say, they’re being hit softer, shorter, and higher – not exactly a good trio. 

Even in his outs, we see a difference. I combed through all of Carroll’s fly balls from the past two seasons to find results closest to his average exit velocity, distance, and launch angle on the season. What I found is that his average fly ball in 2024 looks something like this, whereas in 2023, it looked a lot more like this. To the naked eye, there’s a difference there. 

In Carroll’s case, what’s most interesting is that he acknowledged all of this back in May. According to Carroll, the struggles stemmed from changes he made to his swing in the offseason, which rendered his swing too flat. “My window for success was small,” Carroll told the Arizona Republic. “I was either on top of balls and hitting ground balls, or I’m under the ball and it’s popping straight up.” 

Sure enough, Carroll was right. Vertical Bat Angle (VBA) helps us measure a hitter’s swing path, understanding their quality of contact and ball flight. Typically, a hitter’s VBA is in the range of 25-35, though there are outliers – there are successful hitters with flatter swings, just as there are successful hitters with steeper swings. Still, Carroll is at the lower end of the overall VBA spectrum. So, while his Hard Hit% and Average Exit Velocity are in the 32nd percentile – again, not great, but also not horrible – Carroll’s LA Sweet Spot (the percentage of batted balls hit with an LA between 8 and 32 degrees) is in the 2nd percentile, driven by his flat swing. He’s under the ball too much, so even when he does hit the ball hard, it’s not conducive contact. Nothing flies off his bat.  

You’re probably wondering about a couple of things at this point. First, why in the world would Carroll alter his swing – in a seemingly significant way – after having so much success last season? And, second, if he’s successfully diagnosed the problem (which he seemingly has), then why hasn’t he fixed anything? 

Let’s start with the first question. According to the Arizona Republic, Carroll tweaked his swing to better handle fastballs and cutters up in the zone, a subset of pitchers that Carroll struggled with last season, particularly after the All-Star break. 

Carroll’s holistic numbers show that he handled fastballs last year, posting a .403 wOBA on any fastball offering and a .431 wOBA specifically against the 4-seamer — numbers good for the 92nd percentile. But, looking into them a little deeper, we see why Carroll felt like he had to make a change. 

• Carroll’s 2023 wOBA vs. fastballs pre-ASB: .458

• Carroll’s 2023 wOBA vs. fastballs post-ASB: 334

  
  

The problem is, Carroll’s solution hasn’t worked, either. His .314 wOBA against fastballs this season ranks 231st of all qualified players, slotting him in the 28th percentile. It’s even worse than his second-half numbers from a year ago. 

Sure enough, his flat swing is causing an issue here. Last year, Carroll hit 16 pop-ups against fastballs; he’s already hit 30 this season, with seven more weeks remaining in the regular season. When he hits a fly ball against a fastball specifically, he’s generating far less production. 

• 2023: .602 wOBA and 1.149 SLG

• 2024: .290 wOBA and .524 SLG

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Carroll’s offseason changes have proven counterproductive, and his power has suffered. Carroll has just 35 XBH this season, leaving him on pace to finish about 20 XBH shy of his 2023 total. While he may not look like a prototypical slugger, he’s always managed to generate power from his smaller, compact frame, until now. 

It’s worth mentioning that Carroll’s swing decisions look good – he’s swinging less, chasing less, and making more contact. But, as that combination of events often leads us to, he may be sacrificing power for contact; in this case, altering his VBA in a futile attempt to better handle high heat. 

He’s also pulling the ball a bit less (38.4% to 37%), but that’s not a huge problem, because Carroll has always pulled his ground balls, rather than his fly balls. In each of Carroll’s last two seasons, over 60% of his balls hit to the pull side are on the ground, while over 60% of his balls hit the other way are in the air. Once again, though, it’s the quality of these fly balls that matters. This year, among Carroll’s fly balls hit to the opposite field, his IFFB is 30%; last year, it was 21%. 

Okay, so we see that Carroll’s change – while made with good logic – hasn’t worked. He knows it, we know it. But what’s he doing to fix it?  

Well, incrementally, he’s made his swing steeper. His VBA in July was 23 degrees, the highest single-month mark this season, yet still below his VBA in both 2023 and 2022. Sure enough, his IFFB% in July stood at 13.8% – down 9% from June, and nearly 14% less than April and May. Carroll’s FB% for July (54.5%) was also a season-high. And what do you know, his power came roaring back. Six of his nine home runs this season came in July. While he hit just .221, his .512 SLG dwarfs his numbers from April (.246), May (.343), and June (.370). 

This is substantial progress. It’s difficult to make these sorts of changes in the middle of a season – there’s a reason Carroll made his initial changes in the offseason. But Carroll appears to be on the right path: His swing is a little less flat, and the power is slowly on its way back. 

As the pennant race heats up, the Diamondbacks are already scary – just ask the Los Angeles Dodgers, whose NL West lead has shrunk to a precarious three games. And if Carroll begins to look more and more like his 2023 self, well, the snakes may be more alive than ever.