Corey Kluber finds the zone

Feature photo credit to Keith Allison.

After a blip on the radar, Corey Kluber is back, and the American League should be terrified. Following up on a season in which he snuck on to the scene, became a bona fide ace and stole the AL Cy Young Award from usual suspects Felix Hernandez and Chris Sale, Kluber got off to a rough start to 2015. Four straight starts allowing more than four earned runs in no more than 6.1 innings dropped Kluber to 0-5 to start the season. His ERA ballooned to 5.04 after going 18-9 with a 2.44 ERA in 2014.

Through seven games his average game score was just 48.7, including a mark of 34.25 over those four consecutive losses. To provide perspective, every pitcher starts the game with a score of 50. Kluber sported an average score of 62.8 in 2014, which was fifth best in all of baseball. Kluber also posted just three quality starts through seven outings (42.8 percent), a year after posting 26, fifth most in baseball. Something was off, more than just a drastic decline in run support he received.

Kluber, most of the time, is a strike-firing machine, one that pounds the zone at the start of an at-bat and buries hitters with filthy two-strike breaking balls. This approach allowed Kluber to ring up 269 batters in 235.2 innings in 2014, giving him the second most strikeouts and fourth best strikeouts per nine innings ratio in the majors.

But at the start of 2015, Kluber had some trouble finding the strike zone with the same consistency; in 2014, 67.5 percent of Kluber’s pitches went for strikes. Over his four-start losing streak, he was getting 65.3 percent to go for strikes, according to Fangraphs, with many coming only from batters putting the ball in play. During that span, 11.25 strikes per game came from swings-and-misses and 16.75 strikes per game came looking. In his last two dominant starts, 21.5 strikes per game have come swinging and missing and 20 per game looking, according to Baseball Reference.

To get the full effect of what changed from 2014 Kluber to this year’s early season version, let’s break out the heat maps, with data collected by Brooks Baseball.

This heat map charts every pitch Kluber threw in 2014, in every count to every batter, seen from the catcher’s perspective. As you can see, Kluber generally lives in the strike zone, but looks to put away batters with pitches below and to the right of the right corner, usually with the breaking ball. He rarely aims high of the zone (remember that).


Ck percent pitches 2014

CK 0-0 whiffs 2014CK avg 2014


The next two charts show how many times batters swung and missed on Kluber in 2014 in all situations, and what their batting average was in at-bats that ended with pitches in each location, in all situations. If these charts make anything clear, it’s that Kluber down and to the right of the zone was practically invincible, with batters managing two hits in 42 at-bats and whiffing on 85 percent of swings at pitches in the same location. Kluber often pitched below the zone and found great success there, and in the rare occasion he went high of the zone, he generated a good amount of swings and misses.


CK 0-0 percent pitches 2014


On the first pitch of at-bats last season, Kluber  pounded the zone or tried to get hitters on the left side of the plate with his cutter. If batters went after pitches on the low right corner and beyond, they had very high whiff rates, including 10 whiffs in 10 tries in the lowest right corner.

CK 2 strikes avg 2014CK 2 strikes whiffs 2014


Kluber’s pitch distribution on two strikes in 2014 leaned heavily on the area down and out of the right side of the zone, and he found tremendous success there, with hitters batting less than .050 in each of multiple locations, and in some cases whiffing more than 68 percent of the time. Kluber’s ability to get ahead of the count as early as the first pitch forced hitters into bad situations, and they often chased two-strike pitches unsuccessfully. Kluber won the Cy Young with this approach.

But hitters got aggressive early in counts during Kluber’s 2015 losing streak, preventing him from using the same strategy.


CK 0-0 percent pitches 421 512CK 0-0 avg 421 512


During the slump, Kluber was a little less commanding of the strike zone on 0-0 counts. Though the spot to the right of the corner had often been a good location for Kluber, in this case it did not generate any swings, putting Kluber behind to begin at-bats. This was obviously a much smaller sample size than the 2014 season, but in these four starts, batters were jumping on the first pitch and getting hits on them at greater success rates. All in all, over these four starts, batters accumulated 38 hits on Kluber in 23 innings–13.68 hits per nine innings, very out of line with Kluber’s 7.9 per nine in 2014–and rocked him to the tune of a 6.84 ERA over the span.

So what suddenly clicked for Kluber and turned him back into a pitching superhero? For one thing, batters over his last two starts haven’t been as willing to swing on the first pitch, with 17 first-pitch swings in 57 plate appearances. When they have swung, they’ve been unable to put the ball in play, going 0-for-5 on those 17 swings. The ineffective first-pitch hitting has allowed Kluber to quickly reach two-strike counts, where he has returned to being overpowering his last two starts:


CK 2 strikes whiffs 512 519CK 2 strikes avg 512 519


The putaway pitch low of and outside the right corner has returned with a vengeance, generating six whiffs on six attempts. No batter has gotten a hit on a two-strike pitch in the strike zone, and perhaps most interestingly, Kluber has gone to a new approach of getting hitters with high fastballs. Those four red boxes at the top of the left chart show 11 whiffs on 13 swings at high pitches in or above the upper left side of the strike zone, and an 0-for-12 hitting record, as shown in those same boxes on the right chart.

Hitters ambushed him on the first pitch early this season, but Kluber has reclaimed his dominance of the strike zone at the beginning of at-bats, allowing him to return to using his devastating slurve-type pitch on two-strike counts and rack up strikeouts. Plus, Kluber has started tinkering with a new weapon in the form of the high fastball, and that has aided him to 30 strikeouts and just six hits and one run in his last 17 innings, which included an eight inning, one hit, 18 strikeout masterpiece May 13 against the top team in baseball, the St. Louis Cardinals.

Kluber’s reclamation of the strike zone and new way to get hitters to swing and miss means only bad things for American League hitters. Corey Kluber has returned, and he seems intent on making up for lost strikeouts.

Connor Mount

Connor Mount

Senior Staff Writer at The Left Bench
Connor Mount is an analytics enthusiast, which is polite for "sports nerd." Philip Merrill College of Journalism, University of Maryland, Class of 2017.
Connor Mount
About Connor Mount 164 Articles
Connor Mount is an analytics enthusiast, which is polite for "sports nerd." Philip Merrill College of Journalism, University of Maryland, Class of 2017.