Why is Twins Rookie Brooks Lee Struggling So Badly?

It hasn’t been a smooth rookie season for Brooks Lee. A highly-ranked prospect entering 2024, Lee caught the eye in Spring Training, to the tune of a .963 OPS. Shortly after being assigned to minor-league camp, though, Lee was shut down in late March with what was described as back spasms. Those turned out to be a herniated disc that required two months of rehab, with Lee eventually starting a Complex League rehab assignment in late May. 

Lee debuted with the Twins on Jul. 4, before cranking a two-run home run against the Astros on Jul. 6. In early August, The Athletic reported Lee was dealing with shoulder soreness that ultimately resulted in an IL stint starting on Aug. 9, due to bicep tendonitis. Lee completed a brief rehab stint in St Paul, before returning to MLB action in early September.

Lee has largely struggled during his inaugural big-league campaign. Through Wednesday, he’s hitting .222/.267/.319, with 7 extra-base hits in 37 MLB games. Why include such a tedious overview of Lee’s health challenges to open this piece? Because I don’t want to preclude the possibility that Lee is playing hurt, is incredibly worn down, or both. Any conjecture on his current physical condition on my part would be irresponsible speculation, so let’s focus on the data behind some of Lee’s 2024 struggles. What is going on under the hood here?

Coming into 2024, it was clear Lee had challenges with his right-handed swing. Indeed, it was reported widely earlier this season that Lee had worked feverishly throughout the offseason to correct his poor output as a right-handed hitter in MiLB in 2023. So what has been the fruit of his labor? He’s crushed as a right-handed hitter in Triple-A in 2024. At the major-league level, it’s all been a struggle, with a slightly better performance from the right side.

The dark humor shouldn’t be lost here. Lee worked extensively on his swing against left-handed pitching, which he’s seen in 48 MLB plate appearances, and now looks destitute against right-handed pitching (98 plate appearances). Can you go back to what you were doing in 2023, Brooks?

What about those swings, though? Are they tangibly different in how they are impacting the baseball? Thanks to Baseball Savant’s impeccable timing, we can now answer that question.

A quick primer on Statcast’s relatively new swing metrics: This season, Baseball Savant made swing data public. Here’s some important nuggets before we discuss Brooks Lee. A ‘fast swing’ is defined as a swing at 75 mph or greater. In the first month of the 2024 season, ~25% of swings were classified as ‘fast’. In very general terms, players who swing ‘fast’ more frequently outproduce those who don’t.

Swing length is another metric we’ll use here. Simply, this measures in feet, the distance from the start of the swing to the point the bat impacts the baseball. Again, generally, longer swings produce more power, and often more miss. An average MLB swing is 7.3 feet. So, how do Brooks Lee’s swings plug into all this new fancy mumbo jumbo?

Well, it might not surprise you to learn that Brooks Lee’s swings are shortish (6.9 feet on average) and slow (69.1 mph average). What might surprise you more is how different they are from each other. Lee’s left-handed swing (the one lauded throughout his career) is the slower of the two (68.7 mph vs 69.9 mph on average). Only 2.7% of Lee’s left-handed swings meet the ‘fast swing’ threshold of 75 mph+, compared to 8.6% of his right-handed swings. Lee’s left-handed swing is also a little shorter (6.8 feet vs 7.0 feet). 

It came as a surprise to me that Lee’s erstwhile stronger side per scouting reports (left-handed) is the slower, shorter swing currently. My question is whether there’s a mechanical issue with his swing from the left-side currently, whether technical or injury-related. It’s also worth noting that Lee’s bat speed is significantly below average. That’s not a death knell by any means, but it’s a challenge he has to navigate with a strong approach at the plate.

So, what are some of Lee’s outputs that might be impacted by his swings? It’s worth noting here that Lee hasn’t been particularly good from the left or the right side in his limited MLB playing time, but the right-handed swing is the one currently set up to produce consistently better outcomes.

Any player’s swing metrics are an important piece of the puzzle, but not the only one. It’s important to dig into other data, as our notion of what Lee is as a hitter (currently) is belied by some other intriguing numbers.

What of Lee’s approach, though? Lee talked prior to Wednesday’s series finale against the Angles about how his approach had been ‘in the dumps’. How is this reflection born out, or not, in his data?

Well, he’s right. Lee chases, and I mean a ton. He’s currently chasing at a 34.3% clip, that’s ~15th percentile in MLB and way higher than average (28.3%). Lee chases, and it’s important to note how and where he chases. It’s everywhere. As you can see from the figure below, Lee chases to all compass points, giving pitchers a significant margin for error in devising a plan of attack to induce non-competitive swings.

Additionally, Lee has become a more aggressive swinger, in general. He swung at 47.2% of pitches in July, 54.5% in August, and is up to 57.1% thus far in September. His in-zone swing percentage has fluctuated around its average for the season and he hasn’t seen improved outcomes from swinging more, making me question whether it’s part of a proactive approach, or he’s pressing at the plate.

It’s tough to tie all of this in a bow. Lee has battled through a long season, he’s had two injuries that have impacted and interrupted his playing time. There’s certainly a strong enough minor-league track record to not be overly concerned, long-term. If Lee is going to become a consistent, high-quality MLB regular, he’ll need to improve his swing decisions to raise the lower ceilings his swings currently offer.