Corbin Burnes is proving that spin rate isn’t everything

The 2019 season has been a total disaster for Corbin Burnes. After the former Brewers Minor League Pitcher of the Year burst onto the scene in a relief role last season, he was returned to a starting role. The front office had high hopes for Burnes, but he lasted through only four horrendous starts before the plug was pulled. He seemed to recover when he returned to the bullpen, but a recent seven-run meltdown in Atlanta sent him back to square one. At the time of this writing, Burnes has coughed up 33 earned runs, including a league-leading 14 home runs, in 29 innings. His dreadful 10.24 ERA is accompanied by a 7.34 FIP and 6.62 DRA.

Something that has stood out about Burnes since his debut in the big leagues is his elite spin rate. His fastball spin ranks second in all of Major League Baseball at 2700 revolutions per minute (rpm), and the man ahead of him (Luke Bard of the Angels) leads by only 19 rpm.

Normally, one would see Burnes’ crazy spin and assume that his fastball is an elite pitch. However, that hasn’t been the case—it’s actually been the exact opposite. The pitch has been getting crushed to an almost unfathomable extent. Opposing hitters have raked to the tune of a .619 wOBA, 20.6% barrel rate, and 55.6% hard-hit rate against it. 12 of the 14 home runs Burnes has surrendered have come against his heater, which has proven to be one of the worst pitches in baseball. In fact, per FanGraphs’ linear pitch weights, it’s been the worst fastball among all Major League pitchers with at least 20 innings pitched, and it’s not close. Burnes’ fastball grades out at -19.1 runs above average, with the next closest being Zack Godley at -12 runs.

Burnes’ performance this season tells us that while it can be a valuable metric, a pitcher’s spin rate on its own does not guarantee results. There are a few reasons why his high spin isn’t generating positive results: location, movement, and usage.

Let’s start with location. What’s odd about Burnes is that he likes to throw his high-spin fastball down in the zone. The rule of thumb is that such pitches work best up in the zone. Even last season, Burnes threw plenty of heaters down in the zone or over the heart of the plate, with the difference being that he got away with it. This year, not so much. It doesn’t help that he’s throwing fewer pitches up in the zone compared to last season. He’s utilizing even less of the strike zone, with the overwhelming majority of his pitches being middle-middle or slightly below the belt.

Baseball Savant

Next is movement. While Burnes’ fastball spin is elite, his fastball movement is the opposite. Per Baseball Savant’s new pitch movement leaderboard, it has 15% less vertical movement (or “rise”) than an average four-seamer and a whopping 76% less horizontal movement. In other words, it’s as straight as an arrow. Going back to location, fastballs thrown down in the zone are typically two-seamers or sinkers that generate ground balls. Burnes’ primary offering is a straight four-seamer.

When looking at the pitch movement leaderboard, it’s quickly noticeable that there are over 50 qualified pitchers who have less rise on their fastball than Burnes does. How is it that Burnes’ fastball has been the worst? That’s where usage comes in. Below is a graph of those other pitchers that compares their four-seam fastball movement and usage, with the red data point representing Burnes.

At first glance, it may be difficult to decipher what this graph is saying, so stick with me. The data points represent all of the pitchers who have 15% or less vertical movement than average on their four-seamers. Only six such pitchers have thrown them more often than Burnes has thrown his. That’s all that is shown on the graph, but it gets worse—all six of those pitchers have better horizontal movement on their fastballs than Burnes does, and three of those six have above-average horizontal movement. Not only is his fastball straight, but Burnes is throwing it more often than most, if not all, qualified pitchers with such a straight heater.

We now see how all three issues are working together to create a perfect storm of struggles for Burnes. He throws too many fastballs for having one that doesn’t move much. On top of that, an overwhelming majority of those fastballs are being thrown in a location that does not take advantage of his elite spin rate. Hitters couldn’t square up the pitch last season when Burnes first made his debut, but it’s clear that they have learned his tendencies and adjusted. They’re sitting on straight meatballs down in the zone, a recipe for disaster—and disaster is exactly what has happened. Yes, Burnes’ fastball spin rate may be among the best in all of baseball, but when you look at the whole picture, it’s actually not a very good pitch at all.

Let’s turn our attention to something much more encouraging. For as terrible as his fastball has been, Burnes’ slider has been essentially unhittable. His slider spin rate is also elite at 2,912 rpm, and, even more importantly, it has great movement as well. The breaking ball has 89% more horizontal break than average and 9% more vertical drop. He has commanded it rather well, consistently throwing it down and out to right-handed hitters.

Baseball Savant

The results speak for themselves: opposing hitters are batting .081—yes, .081—against the pitch with a mere .133 wOBA. That’s no fluke, as it’s backed up by a .077 expected batting average and .125 xwOBA. Hitters have swung and missed at Burnes’ slider a whopping 69% of the time (for comparison’s sake, Josh Hader’s fastball has a 46.6% whiff rate). FanGraphs grades it at 5.1 runs above average, good for 16th among all MLB pitchers with 20 innings or more. The only problem is that Burnes has only thrown it 26.4% of the time. The good news is that he’s been throwing it more since his recall from Triple-A (31.6% in May compared to 23.3% in April), but it still doesn’t seem like enough compared to how often he’s throwing his fastball.

How can Burnes turn his season around? It’s going to take a few adjustments.

Improve command of the fastball.
It’s unlikely that Burnes has been throwing fastballs down the middle on purpose. Rather, it’s likely the result of poor command, which extends beyond just those particular pitches. The first step is to address this issue and fix it.

Start pitching up in the zone.
When he hasn’t been throwing cookies down the middle, Burnes has been throwing his fastball down in the zone. His high spin rate isn’t going to do much good in that location. Throwing up in the zone could bring better results.

Throw fewer fastballs and more sliders.
Even if throwing up in the zone leads to more success with his fastball, Burnes should still be throwing it less, as the pitch has little movement and opposing hitters appear to be sitting dead red. In particular, he needs to utilize his best pitch more frequently. While increased usage will likely bring the results against Burnes’ slider back to earth a little bit, it’s clear that it’s a legitimately excellent pitch. It’s time to change up his arsenal so that he’s throwing an equal mix of fastballs and sliders to keep hitters off-balance and take advantage of the one pitch that has been extremely effective for him.

In short, the main issue is that Burnes’ high spin rate is masking the fact that his fastball is a bad pitch. There are adjustments he can make to fix this, but he also needs to rely on his slider more frequently. He’s been throwing it more since returning from his brief stint in the minor leagues, but he still isn’t using it enough. His latest outing against the Reds on Wednesday afternoon provided some evidence that he may be starting to shake up his pitch selection. 20 of the 36 pitches he threw (55.5%) were breaking balls, compared to 15 fastballs. Hopefully, Burnes can make some adjustments and unlock the potential that made him Milwaukee’s top pitching prospect. Make no mistake, the tools (including his elite spin rate) are still there for Corbin Burnes to become a front-of-the-rotation arm. He just needs to figure out how to utilize them.

Statistics courtesy of FanGraphs and Baseball Savant, updated as of May 23.