diamondback Corbin Burnes Remains a Reliable Investment for Long-term Success despite a Decrease in Strikeout Rate
Cheers to the Mystery Squad! After weeks of buzz surrounding whether star free agent pitcher Corbin Burnes would join the Toronto Blue Jays, San Francisco Giants, or his future team, the Baltimore Orioles, he took a turn and inked a six-year, $210 million pact with the Arizona Diamondbacks. The agreement includes an opt-out after the 2026 season.
There's talk that both the Jays and Giants offered more substantial financial pledges than Arizona, but the attractive tax scenario in Burnes' new abode tipped the scales.
Even if it wasn't the most generous offer he had in his possession, it fell within the range estimated by most forecasts as the offseason progressed. There's no doubting the fact that Burnes is one of the consistent top-notch starting pitchers in the game.
There is, however, a significant worry persisting for him. Where did all the strikeouts go? From 2021 to 2024, his strikeout percentage slipped from 35.6% to 30.5% to 25.5% to 23.1%. Going from more than two standard deviations above the average for the league to slightly higher than average, then half a standard deviation above, and finally at the league average from the age of 25 to 28.
At first glance, that looks ominous, and possibly indicates that Burnes' decline phase was in full swing for an ordinary starting pitcher.
However, Corbin Burnes isn't your typical starting pitcher.
Strikeout percentage is undeniably crucial, being one of the three largest cornerstones, and even the most important among them, when evaluating a pitcher's performance. The other two elements are walk percentage and control over contact.
Burnes' walk percentage has varied somewhat through the years, ranging from a low of 5.2% in 2021 to 8.4% in 2023. In three of the last four seasons, it's been well over a standard deviation better than the average, while it's been average in the other season. All in all, pretty noteworthy.
But it's in the contact control area where Burnes truly excels. My measurement for this aptitude is Adjusted Contact Score, which ranks it on a scale where 100 is the league average, with lower values implying better performance. Burnes has been the Contact Master of the Year in three of the last four seasons, registering scores of 75, 93, 82, and 85 between 2021 and 2024.
Interestingly, he doesn't shine in this aspect due to exceptionally high ground or pop-up rates. In two of the last four seasons, he's posted better-than-average liner or ground ball rates, but not by an enormous margin. What sets him apart, however, is his ability to suppress the power of hitters' batted balls.
In his three Contact Master of the Year seasons – 2021, 2023, and 2024 – he's limited hitters to average exit speeds a full standard deviation below the league average. Even better, he's curbed power across all batted ball types. His fly ball authority allowed has been over a standard deviation below the average in all three seasons, and both his liner and ground ball authority allowed has been above a half standard deviation below in all three seasons, and over a full standard deviation below in one of the three. It's a display of consistent excellence.
So you might say to me, sure, but the Diamondbacks are investing heavily in what Burnes can do in the future, and his strikeout percentage is plummeting.
To you, I say, remember Zack Wheeler.
Everyone knows about Wheeler's greatness today, but he didn't reach anywhere close to his current level of pitching until 2018, at the age of 28, the same age Burnes was in 2024. His strikeout percentages have fluctuated dramatically over those years, from a low of 18.4% in the shortened 2020 season to 29.1% the next year. Since 2018, his walk rates have significantly improved, going from good to bordering on excellent. His one constant? Exceptional contact management, achieved through the suppression of authority, just like Burnes.
Since 2021, Burnes' average Adjusted Contact Score has been an impressive 84. Since 2018, Wheeler's average Adjusted Contact Score has been......an impressive 84. He's only been Contact Master of the Year once, in 2020, but has come up short just by a fraction in multiple other seasons (including to Burnes in 2023).
Since 2021, Burnes' "True" ERA- (my batted ball-based estimate of ERA-) is 68. Since 2018, Wheeler's "True" ERA- is 72. The disparity is due to Burnes' exceptional 2021 season (48 "True" ERA-). Barring injury (a major concern when extending a large, lengthy contract to a pitcher), I'm betting on Corbin Burnes aging in a similar manner to Zack Wheeler. Solid strikeout percentages, decent walk percentages, and sustainably superb contact management performances.
Corbin Burnes' peak performance might be behind him. 2021 was Hall of Fame-worthy stuff, far superior to the greatness showcased by Tarik Skubal in 2024. But a series of cookie-cutter MVP-caliber seasons seem to be Burnes' likely MINIMUM over the length of this contract. The Diamondbacks have certainly got themselves a bargain.
The Philadelphia Phillies and the Baltimore Orioles were also interested in acquiring Corbin Burnes, but they failed to match Arizona's attractive tax scenario. Zack Wheeler, who had similar struggles with strikeouts early in his career, eventually transformed into a top-tier starting pitcher, and Burnes' performance trajectory might follow a similar path.