That's the question Russell Carleton of Baseball Prospectus asked in this analysis. From 2011 to 2014, including the postseason, Los Angeles Dodgers pitcher Clayton Kershaw is 3-7 with a 4.83 ERA against the St. Louis Cardinals and 70-22 with a 1.99 ERA against everyone else. So ... that led to some speculation, most prominently by Harold Reynolds during the game broadcast, that the Cardinals were stealing signs. Ex-major league pitcher Danny Graves argued that Kershaw was tipping his pitches, since Kershaw hadn't pitched from the stretch until that big inning in Game 7.
Most people -- including the Dodgers and Cardinals -- quickly dismissed the stealing signs thing, saying players don't really do that anymore. The tipping pitches idea is more plausible, but leads to the obvious question: Only the Cardinals have figured that out?
Anyway, Russell points out that Kershaw's stats versus the Cardinals and versus everyone else are pretty similar except for one thing: Batting average on balls in play. Against the Cardinals it's .343 and against everyone else it's .280 (again, all numbers since 2011). Russell writes:
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.
Of course, if you believe in the tipping pitches theory, you can simply argue that the Cardinals have a higher average on balls in play against Kershaw because they know what's coming. None of the hits against Kershaw in Game 1 were cheap. All were hit hard, either ground balls up the middle or line drives. Grant Bisbee of SB Nation had a good piece showing all 29 pitches in that seventh inning, arguing that Kershaw was simply missing on location and the Cardinals didn't miss.
In this case, I wouldn't necessarily ascribe it to "luck" since the Cardinals hit bad pitches -- Kershaw's fastball, in particular, was up in the zone and over the plate -- as much as even the best pitchers can have terrible innings. (And give credit to the Cardinals.)
It's certainly understandable why everyone reacted with such surprise over Kershaw's sudden demise in that game: He'd had one bad outing all season, when he allowed seven runs in 1.2 innings against Arizona back on May 17. That was the only game he allowed more than three runs all season. I've watched that inning and it was a little different from the Game 1 outing, one that conforms more to the idea of bad luck. Kershaw gave up a walk, a bad-hop single off the dirt near the plate that bounced over Adrian Gonzalez's head and another broken-bat single through a drawn-in infield. On the other hand, he struggled to throw his curveball for strikes and the Diamondbacks hit three triples in the inning, all hit to deep left-center or center. Only four times did a team hit three or more triples in a game this season and the Diamondbacks did it one inning off Kershaw. So it was a combination of bad pitching and some bad luck.
Maybe the bigger story here is what Russell alluded to: We (fans, media) like to portray the postseason as a test of wills and intestinal fortitude. Kershaw has been the best pitcher in baseball the past three seasons. We like him. He's fun to watch. We want the postseason storyline to follow the regular-season one (well, unless you're a Cardinals or Giants fan). Kershaw hasn't delivered us that storyline, either in last year's NLCS or in Game 1.
And if he gets hammered again Tuesday? We'll start hearing stuff, negative stuff. Maybe there will be some truth to it, maybe not. I don't think anyone really knows, but I won't be one to question Kershaw's mental toughness. If he gets beat, he gets beat.
That said: If you're going to be compared to legends like Koufax ... well, you gotta come up big in the postseason.