October 7, 2014
The Cardinals Do Not Own Clayton Kershaw
We begin here with a Tweet sent out by former MLB player-turned-pundit Marlon Anderson
Clayton Kershaw had a nightmare seventh inning against the Cardinals on Friday night, in which he coughed up eight runs and the substantial lead that the Dodgers had staked him to. Kershaw’s last three playoff appearances (Friday, plus Games Two and Six of last year’s NLCS) have all been losses to the Cardinals. And yes, the numbers that the MLB Network graphic showed are true, in the sense that Kershaw really is 3-7 against the Cardinals over the last few years. And of course, Mr. Anderson wants you to believe that there can only be one possible explanation: The Cardinals have somehow solved Clayton Kershaw. They are in his head.
Ah, but how the numbers can deceive!
Dissecting the graphic, we see won-loss record (*sigh*), win percentage (which is just the same info as above), ERA (that’s at least reasonable), opponent average (a clue hiding in plain sight!), and strangely, innings per start (huh?).
Let’s keep the same timeframe (2011 to 2014, including the postseason) and look at some other numbers that could have gone on that screen.
We see that even on these stats, Clayton Kershaw has pitched somewhat worse against the Cardinals than the rest of the league. This shouldn’t surprise anyone. It’s comparing Kershaw’s performance against a good team to his performance against the league average. In fact from 2011 to 2014, the Cardinals finished 5th, 5th, 3rd, and, uh, 24th in runs per game in all of MLB. But we see that Kershaw hasn’t fallen apart against the Cards. Just done a tiny bit worse.
There might be people out there who aren’t familiar with why I picked these stats to highlight. One of the foundations of baseball research is that if you want to get to know a pitcher, look at his strikeout, walk, and home run rates. The reason is that a pitcher who is good at striking hitters out in one year is very likely to be good at striking hitters out in the following year. Same goes for a pitcher who is good at avoiding giving up walks and home runs. What happens when you take away walks, strikeouts, and home runs? You’re left largely with singles, doubles, triples, and outs on balls in play. These are all events which depend, at least in part, on the fielders behind the pitcher. What we find is that the results of these types of events (this is called “batting average on balls in play” or BABIP) do not stay the same from year to year. In fact, the results from one year to the next are nearly random. There’s been a lot of work showing that BABIP isn’t completely and totally random, but over a few hundred batters faced, there’s a lot of luck that drives a pitcher’s performance.
Yes. Luck. Sure, the fact that the ball got through the infield for a hit still counts on the scoreboard, but the way that stats like wins and ERA (and the #NarrativeMachine) give out credit assumes that the pitcher is completely at fault (or on a ball that’s caught, completely to be credited) for what just happened. That just isn’t the case. A pitcher might give up a screaming line drive that just happens to be hit right at the shortstop.
In general, most pitchers end up with a BABIP of around .300 in each year. But because of the luck factor, some end up in the .260s and some end up in the .340s. The swings in fortune can be that big. Their ERAs either rejoice in or suffer for this luck, but that swing in ERA is not indicative of who they are as pitchers. If you want to know what a pitcher is going to do in the future, a guess based on his strikeouts, walks, and home runs allowed (there are several, the one I used here is Fielding Independent Pitching or FIP) is actually better than using his ERA at the time. It’s better because it strips out the effects of luck. And Kershaw’s FIP is only slightly worse against the Cardinals than against the rest of the league. We see from the table that Kershaw’s FIP against the Cardinals is 2.78. That means that when we account for how unlucky Kershaw has been in the past, he has actually pitched much more like a guy with a 2.78 ERA than a guy with a 4.83 ERA. Suddenly, Kershaw looks like an ace again.
How un-lucky has Clayton against the Redbirds? When we look at Kershaw’s performance against the Cardinals, we see that his BABIP is quite high at .343. I know that during the postseason everyone likes to pretend that games are won and lost based on magical fairy dust, grit, and character. But frankly, a lot of what drives a baseball game is dumb luck. That’s not comfortable for people to hear, but the sooner that you accept that, the sooner we can have a real conversation about baseball. Mr. Anderson, you can take the Dodger blue pill and accept it or the Cardinal red one and this will all be a fantasy. Clayton Kershaw has gotten very unlucky over the last four years against the St. Louis Cardinals, and luck is not a character trait. Luck just kinda happens. If you made bets on a series of coin flips and won seven in a row, that would be an unlikely event (though possible). Yes, you still have the money you just won in your pocket, but it’s not because you have a special skill for calling coin flips or because you are a morally righteous person. You caught a run of good luck. Congrats. Don’t expect it to last.
Dodger fans who are worried about what might happen in Game Five (if the series gets that far) or Game Four (if Kershaw goes on short rest) against the Cardinals because St. Louis seems to have CK’s number, take a nice deep breath. Your ace does not crumble whenever he sees two red birds balanced on a bat. The Cardinals should get credit for being a good team and even, in the past, for adapting their strategy at the plate to suit the situation. But they do not “own” Clayton Kershaw. In fact, on the things that Clayton Kershaw controls, he’s actually pitched like an ace against the Cardinals over the past few years. And that’s what you should continue to expect if the Claw gets another chance to pitch against the Cards.