Sabermetrics

Can Gerrit Cole Return to Ace Form With Astros?

As you have probably heard by now, Gerrit Cole is the newest member of the World Series champion Houston Astros starting rotation. For the past few days, Astros fans have probably been scouring Gerrit Cole’s statistics from years past and been disappointed by what they saw. Despite Cole’s pedigree as the former number one overall pick and top 5 Cy Young finisher in 2015, he has been quite pedestrian the last two seasons. In fact, last year Cole was almost an exactly league average starting pitcher, posting an ERA+ of 101. Despite Cole’s roughly average performance the last two seasons, there is reason to believe that Cole could regain his ace form in Houston.

The first reason to believe that the Astros may be able to get more out of Cole than the Pirates have the last two years has to do with the right-hander’s declining fastball. While the former number one pick still posts elite velocities with the pitch, hitters are increasingly able to catch up with the pitch.

The following tables shows how opponents have fared against Gerrit Cole’s fastball over the last three years:

Opponent xwOBA v/ FB Exit Velocity v/ FB Launch Angle v/ FB ISO v/ FB
2015 .322 89.0 mph 8.7° .104
2016 .332 87.5 mph 9.5° .133
2017 .347 86.7 mph 11.7° .189

The important thing to note here is that although opposing hitterrs have posted weaker exit velocities against Gerrit Cole’s fastball each of the last two seasons, they have increased their launch angle against the pitch, resulting in both a higher xwOBA and isolated slugging percentage against the pitch. This suggests that although Gerrit Cole has maintained his velocity (96.48 average fastball velocity in 2017), hitters are keying on his fastball and doing more damage when they put it in play.

This is a troublesome trend considering Cole’s reliance on the pitch. Over the last three seasons, Cole has thrown either a four-seam or two-seam fastball over 58% of the time and has insisted on its continued use despite it becoming less effective each of the last two seasons.

With Cole’s main weapon taken away from him, there is no doubt that he has become a lesser pitcher. Thankfully, this could change in his new home.

In 2017, the Astros threw the second lowest percentage of fastballs in the MLB (29.4%), trailing only the Rangers in that category. Many pitchers on the Astros staff implemented less fastball heavy approaches and enjoyed resurgences as a result. Take, for example, reclamation project Charlie Morton. The right-hander (who used to be a teammate of Cole’s), threw a career-high percentage of curveballs (28.3%) and a career low number of fastballs en route to a career-high whiff rate.

Morton is not the only Houston hurler who has reaped the rewards of this strategy. Starting pitcher Lance McCullers throws the highest percentage of curveballs in the game and multi-inning relief weapon Chris Devenski throws the second highest percentage of changeups. This can be partly explained by the fact that both of these guys have particularly nasty offspeed pitches, but it also speaks to the Astros pitching philosophy.

While this strategy has proved helpful for a number of Astros pitchers, it should be noted that this approach is only effective if the pitcher employing it has other pitches at his disposal. Luckily for the Astros, Gerrit Cole does.

With both a curveball and a slider, Cole has two quality breaking pitches that we can expect him to utilize more this season. Over the past three seasons, Gerrit Cole ranks in the top 20 amongst qualified starting pitchers in whiff rate on his slider. Unsurprisingly, his best year with the pitch came in his 2015 campaign, when he threw the pitch a career-high 21.13% of the time and had the 15th highest whiff rate in the league.

While his slider has been his most effective offspeed pitch, his curveball has all the makings of an elite offering. Cole’s bender ranks in the 74th percentile in Spin Rate, the 79th percentile in horizontal movement, and 76th percentile in velocity. Despite this, he threw his curveball just 12% of the time in 2017. This was actually a career high for Cole, but he still utilized it far too infrequently.

There has been data to support the notion that curveballs with high spin rates such as Cole’s are the most effective after low-spin fastballs. With this in mind, the Astros should have Cole follow fastballs with curves, considering his heater ranks in just the 27th percentile in spin rate. This pitch pairing could be deadly if utilized more frequently, but I am sure the Astros already know that. Just for fun, here is a look at Cole punching out one of the game’s best hitters with a nasty curve.

Cole.gif

While Statcast data helps augment my argument, we really don’t have to look far to reach the conclusion that Cole would be better served by leaning more on his breaking pitches.

Consider the following table comparing how batters have fared against Cole’s breaking stuff in relation to his fastball:

Fastball Curveball Slider
Batting Average .274 .231 .210
Slugging Percentage .406 .327 .331
Home Runs 45 5 13
Whiff Rate 6.81% 14.03% 18.82%

This chart comes with the caveat that Cole has yielded more home runs when throwing his fastball due in part to a higher usage rate, but the fact remains that Cole’s other offerings have netted better results so far in his career.

This data is only showing the balls that hitters choose to offer at, but what about the pitches that batters lay off? In other words, hitters do less damage versus his breaking ball when they put it in play, but how well does Cole command his offspeed stuff?

The answer is quite well. In fact, Cole has a strike percentage of 32.77% on his slider and 34.56% on his curveball, which are both higher than his fastball, which he throws for a strike just over a quarter of the time.

Just in case you were wondering, I have been ignoring Cole’s changeup for the entirety of this article because he throws it less and has had less success with it compared to his other offspeed pitches. I wanted to make sure I noted that he does feature a changeup from time to time, but the numbers lead me to believe that the adjustments he makes with the Astros will not revolve around increased changeup usage.

All in all, Cole has an extraordinary arsenal of offspeed pitches, but the over-reliance on his fastball has hurt his performance, particularly in the last two seasons. Now that Cole is a part of a team that has adopted a more breaking ball oriented approach and has had great success in doing so, Astros fans should expect a new and improved Gerrit Cole in 2018.

Tagged , , , , , , ,

About Traven Tapson

I am a recent graduate from Claremont McKenna College pursuing a career in baseball operations for an MLB team. I am fascinated by the analytical side of baseball and use this blog as a platform to share my insights and knowledge with those who share my curiosities.
View all posts by Traven Tapson →