Corey Kluber Rides the High Strike into History

Corey Kluber just regressed very quickly. After a high-profile winless start to his post-Cy Young-winning campaign that had many wondering what was wrong with him, the Cleveland right-hander struck out 18 Cardinals yesterday over eight innings, allowing only one hit and no walks along the way. In reality, there was nothing wrong with Kluber; his 5.04 ERA was mostly a mirage overlaying a 3.20 FIP, and given the fact that his peripherals were almost in line with last year’s stellar figures, better times were always ahead.

The better times came all at once, however, and they came in a package that almost made (and did make) history: Kluber finished the eighth inning just three strikeouts shy of the single game record for most in a game, 21. He didn’t get the chance to go out for the ninth, something that is being hotly debated, but the facts speak for themselves: Kluber had the most strikeouts in a game since 2004, he was only the second pitcher ever to have 18 Ks in eight innings (Randy Johnson, 1992), and his game score of 98 was the highest in an eight inning outing since 1914.

I won’t list all of the records because there are a lot of them, but the bottom line is that he had an almost impossibly great day. August summed up the impact on Kluber’s season stats well in this tweet:

That’s quite a turnaround, as you might expect, so let’s dive a little deeper into the start. We’re going to kick this off with a GIF. It’s a good GIF, and it illustrates a few points we’re going to talk about. The camera angle changes slightly as the innings progress, but it still gives us a pretty good idea of where Kluber was operating yesterday. Green circles are swinging strikeouts, red circles are looking strikeouts:


I did my best to mark exactly where the ball crossed the plate, and look at how big the zone gets by the end of the game. Kluber and Roberto Perez inch out on either side in small increments, dictating the strike zone. The last frame where we can see all of the 18 strikeouts is really what tells us something interesting. Look at all the high swinging strikeouts above the belt. By my count, there are eight of them, so they account for almost half of his total. Now look at his strikeout heat map from last year, courtesy of Baseball Savant (from the catcher’s perspective):


His strikeout heat map this season previous to this past start was much the same: a big hole in the upper part of the zone. We know about the great slider and curveball he has; they show up every start as his main out pitches. So what made the high fastball so effective as a strikeout tool this time around?

One of the reasons was his ability to throw his hard slider (sometimes classified as a cutter because it’s so hard) and curveball for strikes. Before yesterday, Kluber had thrown his slider for a strike 36% of the time in 2015; yesterday, it was just shy of 50%. His curveball tells the same story, as he located it at will on the outside corner for called strikes, especially against lefties. With eye levels changed, and the ability to spot the breaking stuff, Kluber climbed the ladder with two strikes — racking up strikeouts near the letters.

Yes, his velocity was great, but no greater than it has been the past few starts, and the movement on all of his pitches was in line with what we’ve seen this year so far. Kluber simply commanded all of his pitches, expanded the outer edges of the strike zone early in the game, and was deadly with the high fastball.

The other main note we should make with this game was that it came against a very good offensive team. When these sorts of dominant pitching performances occur, they’re often against weaker opposition, or teams that have an exploitable vulnerability: the Cardinals aren’t really one of those teams. Going into yesterday’s game, they had the 7th-lowest strikeout rate in the majors, the 7th-highest wRC+, and the 4th-highest OBP. They are an above-average offensive team that hadn’t scored fewer than three runs in a game in almost two weeks.

With that in mind, let’s run a fun experiment to compare Kluber’s game to a few other masterful pitching performances, seeing how easy or difficult the opposition team was to strikeout compared to the rest of the league for that year. Let’s set the bar for pitchers high:

• At least eight innings
• At least 15 strikeouts
• One hit or less
• No walks

There are only three other games since 1914 that fit that criteria: Kerry Wood’s famous 1998 20-strikeout game against the Astros, Pedro Martinez’ 1999 17-strikeout game against the Yankees, and Clayton Kershaw’s 15-strikeout start from last year against the Rockies. This is special company.

We’ll look at the strikeout rates of each team these four pitchers faced for the entire season leading up to the game in question. Since we know strikeouts are a little different in 2015 than they were 15 or 20 years ago, we’ll adjust them quickly to get the difference of each team from the league average for that year. Let’s call it K%-. Since strikeouts are (usually) bad for a team, we’ll make it so that values over 100 (league average) mean the team the pitcher faced was more prone to strikeouts, while values less than 100 mean the team was less prone to them. Here are the results (I’ve noted the number of strikeouts for the pitcher, as well as which team they occurred against):


It’s very difficult to discount a 20-strikeout game, but if you were to do it, you’d say the Astros were more prone to striking out than the average team in 1998. Out of this sample, only the Yankees that Pedro faced in 1999 were less strikeout prone than the Cardinals Kluber faced yesterday, and the Yankees won the World Series that year. Pedro actually gave up a home run to Chili Davis as his only hit of that game in his nine innings of work, so we can now commence the argument of whether Kluber might have had the better game. For what it’s worth, both games have a Game Score of 98.

That seems like a narrow and elite scope, though, so let’s lower the bar a little bit. How about this: let’s allow a couple walks, with all else equal to our last sample. That widens the pool to 14 games, with a lot of names we know: Warren Spahn, Randy Johnson, Nolan Ryan. Unsurprisingly, almost all of the games are post-1990, so that at least cuts down on the trouble with comparing across vastly different eras of baseball. Now let’s chart those starts by K%- to see who the hardest opposition team to strike out was compared to their league average:


There’s a more even distribution of high- and low-strikeout teams than I would’ve anticipated, but Kluber is still in the top three when it comes to strikeout difficulty compared to league average in each season’s environment. This doesn’t mean that Kluber should be compared directly to high strikeout games from very different eras; the impact of differing mound heights (in one example) and offensive approaches on strikeout rates throughout history are beyond my realm of knowledge to judge.

I’m fairly comfortable with comparing him to most of the pitchers in this sample, however, given the strikeout research we have. What we really take away from this exercise is that the Cleveland right-hander had one of the best strikeout games ever while facing one of the hardest teams to strikeout compared to the rest of the league during a given season.

Corey Kluber has probably always had this in him — with a big fastball and two great breaking pitches, everything just needed to work perfectly in tandem on one specific day. Yesterday, everything lined up in the form of impeccable command and airtight pitch sequencing, allowing him to expand the strike zone and use a two-strike pitch (the high fastball) that isn’t traditionally available to him. There was never anything wrong with Kluber, and he decided to regress all at once. The Society is strong.

Owen Watson writes for FanGraphs and The Hardball Times. Follow him on Twitter @ohwatson.

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the frame in the picture moves from AB to AB, so the strike zone is not as big as it looks by the end. Especially the called strikes to the RHH that by the end look like they are in the middle of the box, when they are called initially they appear to be very close to the black of the plate.


Good point, you can clearly see the position of home plate shifting relative to the (unmoving) second green circle on the lower left corner of the zone