Corbin Burnes proves the sinker is not dead

The 2019 season was one to forget for Corbin Burnes. After a good-but-short stint for the Milwaukee Brewers in 2018 which included some memorable playoff performances, he seemed all but a surefire breakout candidate. The opposite outcome happened, however, as he pitched to a grotesque 8.89 ERA/6.09 FIP in 49.0 innings of work. Rather than fulfilling his promising outlook, he was demoted to Triple-A, and then again to Double-A.

Despite the forgettable, double-demotion earning campaign, there was reason for optimism. For one, Burnes still missed a ton of bats—his strikeout rate climbed from an already good 23 percent in ‘18 to an outstanding 29.8 percent in ‘19. There was also some evidence of batted ball misfortune. Burnes’s actual ERA was more than three whole runs higher than his 5.73 xERA (per Baseball Savant), and his 6.09 FIP was heavily buoyed by a whopping 38.6 percent rate of fly balls finding their way over the outfield fence. All you had to do was look at his 3.37 xFIP to realize that better days were ahead.

Even though the ‘do nothing different and hope for better luck’ strategy probably would have worked for Burnes, it clearly wasn’t good enough for him. Instead, he went with the ‘do everything different and hope for better luck’ strategy. I’m not quite sure which of the two would have been a bigger gamble, but what I do know? Burnes’s decision paid off, pitching to an immaculate 2.11 ERA/2.04 FIP/2.99 xFIP in 59.2 frames. Moreover, his HR/FB% nosedived to just 4.7 percent.

Now, let’s address the elephant in the room. Yes, both of these are rather small samples. Yes, certain metrics like HR/FB% are meant to regress over time. Clearly, 38.6 to 4.7 percent is an overcorrection—an act of contrition on behalf of baseball gods, perhaps. It wouldn’t be prudent to think that such a low mark like that will hold. However, to dismiss Burnes’s progress to small sample size and regression to the mean would be to gloss over the changes he made last offseason, which included completely retooling his pitch arsenal.

In ‘19, Burnes was mainly a two-pitch pitcher, relying on the fourseam fastball 52.5 percent of the time, throwing his slider—his best pitch by far—31.0 percent of the time. While he dabbled with four other offerings, they were mostly absent. In ‘20, his percentages nearly flipped, as his two least thrown pitches became his two most thrown pitches. Burnes still threw the slider quite a bit, but only 13.7% of the time. As many pitchers in today’s game trade their sinking two-seamers for rising fourseamers, Burnes did the exact opposite, relying on the two-seamer for one third of his pitches while throwing the fourseamer just 2.5 percent of the time.

Here is the breakout from Baseball Savant for a better visual:

With the new sinker/slider combo, Burnes was able to better to command both sides of the plate, keeping the sinker to his armside and his cutter to his gloveside. The combo especially became a weapon against lefties, as Burnes made his platoon spit virtually disappear. In ‘19, lefties had a .449 xwOBA, and in ‘20 they struggled to a .270 xwOBA. In other words, left handed hitters went from Juan Soto to Rougned Odor in a matter of one year.

Below is a gif of the two pitches back to back, followed by an overlay:

As you can see, the two pitches play off each other naturally. Additionally, the rest of Burnes’s pitch arsenal proved better as a result, as the secondary offerings played up better against the two primary ones. Instead of being a two pitch pitcher as he was in ‘19, he had six legitimate major league offerings in ‘20.

The fruits of all these changes bore a 2.4 fWAR which was good for the fifth-highest total in the National League. Had he recorded one more out and qualified for the ERA title, he may have received more Cy Young consideration. Along with an increased ability to get swings and misses at an elite clip (36.7 K%), Burnes also ranked among the best in baseball when hitters did make contact, the area that plagued him a year ago. His .361 xwOBA in ‘19 netted him an 11th percentile ranking, while his .266 xwOBA in ‘20 netted an 82nd percentile ranking.

In all, Burnes’s efforts resulted in an impressive turnaround for the young righty. Pivoting from a fourseamer to a sinker, he dared to go against the grain, and it paid off. While some of his metrics like his HR/FB% will most certainly show negative regression in 2021, it’s a safe bet that he will continue to build upon the success of his ‘20 season.

Brian Menéndez is a contributing writer for Beyond the Box Score, as well as a senior writer for DRaysBay. Additionally, he has been featured in The Hardball Times. You can find Brian on Twitter at @briantalksbsb.