Over the past two full seasons, there hasn’t been a better starting pitcher in baseball than the Brewers’ Corbin Burnes. Strikeout rate? Way better than league average. Walk rate? Same. Contact management? He was the NL Contact Manager of the Year in 2021, and was solidly above average in 2022. Quantity, quality, any way you look at it, Burnes was the gold standard among National League starting pitchers.
Going into the 2023 All Star break, Burnes was merely very good this season. His strikeout and walk rates were well off of career norms, and while his contact management performance was still quite good, he didn’t project to be in any award discussions.
Then he came out of the All Star break like a house afire. 14 shutout innings, only four hits (all singles) allowed, and a gaudy 23/3 K/BB ratio. And these starts were against the Reds and Phillies, two of the hottest teams in the game going into the break, both on the road. So is Corbin Burnes back? Was he ever gone?
To answer the last question first, peak Burnes did appear to be missing in action. His swing-and-miss rate stood at 11.8% at the break, down sharply from 15.1% last season and 16.6% in 2021.
Burnes first made his mark at the game’s highest level with his electric cutter. He’s the only starter in the game who throws his cutter over half of the time, but with such heavy usage came familiarity. Each season I grade out each pitch in the repertoire of starting pitchers with over 135 innings pitch, measuring their bat-missing and contact management performance relative to the league. Burnes got “B+” grades for the pitch in 2020 and 2021, and that was misleadingly low.
This is because I lumped cutters in with splitters, as the population of pitchers throwing either offering was too small on its own. Splitters in general are more effective than cutters, so the latter suffered in comparison. Among its own, Burnes’ cutter was a clear “A” or even “A+” offering. He recorded 15.1% and 15.0% whiff rates with the pitch in those two seasons.
Last year, the number of starters throwing those pitches increased to the point that I could measure cutters vs. cutters and splitters vs. splitters, and Burnes’ cutter received only a “B” grade against weaker competition. Its pitch-specific whiff rate dropped way off to 12.1%, and its contact management performance fell into the league average range. Plus, its usage leapt from 31.5% in 2020 to 55.4% in 2022. He was becoming increasingly reliant on a pitch that was declining in effectiveness.
And it wasn’t like he didn’t have viable alternatives. Both his curve and slider received “A+” grades in 2022, and he threw them only 18.4% and 9.2% of the time, respectively. So as 2023 got underway, it was status quo for Burnes, who used his cutter 54.4% of the time through the All Star break. with his curve (16.8%) and slider (7.3%) being used less.
In his first two starts after the break, Burnes made one big change – he started using his curve more, partially at the expense of his cutter. While he still used his cutter 50% of the time, his curve usage spiked to 27.7%. And the curve has been exceptional – he’s notched an otherworldly 30.4% whiff rate in those two starts.
His dominance has been total – small sample, sure, but 45.1% K rate? 5.9% BB rate? Only one line drive or fly ball above 100 mph? Total and complete mastery. Peeling another layer deeper, there is one other clear upward trend.
You might recall that Burnes was one of the more notable pitchers first caught up in MLB’s crackdown on sticky stuff that boosts spin rates. It should be noted that Burnes’ four most effective pitches’ spin rates have jumped since the break – his cutter (2690 rpm after the break, 2656 before), curve (2860 vs. 2779 rpm), changeup (2065 vs. 2039 rpm) and slider (2863 vs. 2806 rpm) have all moved upward over his past two starts.
Even the game’s best pitchers continuously are looking for edges here and there to maintain their standing or even find that extra 1-2% of greatness. Burnes realized he needed avoid becoming overly reliant on his cutter, and luckily had a couple of excellent secondary pitches to handle some of the overflow. He does everything well, and simply must remain healthy to retain his standing as one of the game’s best. To his credit, Burnes is not satisfied with that, and seems to be in the process of exploring his ceiling as we speak.
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Read More: Don’t Look Now, But Brewers’ Corbin Burnes Is Rounding Into Peak Form