Last season led the MLB to the extremes of curve-balling rates.
Since 2002, the first season of pitch tracking, four of the top six teams in single-season curveball usage came from last season (starters only). In third was the 102-win Cleveland Indians, in fourth was the 104-win Los Angeles Dodgers, in fifth was the 101-win Houston Astros, and in sixth was the…66-win Philadelphia Phillies. It’s probably just coincidence that the three best teams threw the most curveballs. But that’s not what this article is about.
The Indians led the league curveball rate in 2017, with their starting pitching staff throwing 20.6% curveballs. They were historically extreme last season, but they weren’t all that extreme last season compared to last season. The Dodgers starters threw curveballs 20.1% of the time and the Astros starters threw curveballs 19.4% of the time. But no matter what time period you want to look at, they were extreme in curveball effectiveness.
Pitch values are not the best evaluator of success, but they can give you a good indication of success with enough of a sample. Atop the starting pitcher curveball pitch value leaderboard for 2017 sits the Indians, accumulating 56.3 runs of value. The Diamondbacks come in at second with a run value of 25.6. The difference between those two teams is the same as the difference between the Diamondbacks and the 13th place Reds. Going back to 2002, no team comes even close, with the 2003 Cubs ranking second with 30.9 runs. Obviously, though, if they threw curveballs that much, they are going to rank highly. Using standardized pitch values, which measure run value per every 100 pitches, the Indians ranked first last season with a 1.80 mark. The Yankees were second, posting a not very close 1.35 figure. Since that 2002 season, Cleveland’s standardized pitch value from last season ranks third.
It may be easier to visualize the ridiculousness. Below is a plot of the curveball rate (as a decimal) of every individual team single-season since 2002, along with their standardized pitch value. The 2017 Indians are in orange.
Almost no team has matched their curveball run value in general, but accounting for the frequency with which they throw it, 2017 Cleveland is on another planet. No team that threw curveballs at least 15% of the time comes close to touching the Indians pitch value from last season. How were they this good?
Corey Kluber’s absurd breaking ball is up to debate whether it is a slider or a curveball, but Fangraphs pitch type classifies it as a curveball, so it is a curveball for this purpose. Since 2014, Kluber has accumulated 97.9 runs of pitch value on his curveball. In that same time period, no other team as a whole has accumulated more than 40.9 runs. Which isn’t that surprising when the pitch looks like this:
It’s not all Kluber though. If you remove his 37.8 run value from the Indians 2017 total, the team would still rank fourth overall with 18.5 runs. Let’s look at what the rest of their rotation was putting on hitters.
When you think of Carlos Carrasco and his breaking ball, you probably think slider, but he’s jumped on the curveball train. After throwing it less than 10% of the time in 2013-15, his curveball usage climbed all the way 16.2% last season. It didn’t lose any effectiveness:
For Trevor Bauer, his curveball is how he’s found success for most of his career. So why not throw it more? That’s just what Bauer did, bumping it’s usage from 19.4% in 2016 to 29.8% in 2017 en route to a breakthrough season. Who knows how to get a pitch to move like this:
Josh Tomlin never threw his curveball more than 15% of the time in any previous season, but used it 24.1% of the time in 2017. The Indians may be on to something:
In his sophomore season, Mike Clevinger shaved more than two runs off his 2016 ERA of 5.26. He also doubled his curveball usage to 11.6%. Here it is:
All of these guys were in Cleveland in 2016, yet the starting rotation ranked “only” seventh in the league with a 4.08 ERA. In 2017, the starters ranked second with a 3.52 ERA. The trend here is clear. All of these guys, including Kluber (who went from 19.7% to 27.4%), significantly increased their curveball usage. All of them had career years.
It’s evident that Cleveland came together as a staff and made a decision to throw their breaking balls as much as possible. It appears to have worked. As noted by Jeff Sullivan, the Indians may have had the best pitching staff of all time last season. That includes their incredible bullpen, but the starting rotation held up their end of the bargain as well.
The team did something unbelievable in 2017. Cleveland combined historical curveball usage with historical curveball effectiveness. All five of these pitchers return next year. Don’t be surprised if the Indians stretch the bounds of curve-balling even more in 2018.