Proven Postseason Performers, and Other Nonexistent Tongue-Twisterson October 20, 2020 at 5:50 pm

Proven Postseason Performers, and Other Nonexistent Tongue-Twisters

I probably don’t need to write this article. If you’re reading it, you’ve navigated to FanGraphs, which already implies a certain willingness to “trust the stats” and “look at the evidence,” those kinds of things. It’s playoff time, though, which means that on TV broadcasts across the land, a motley crew of players are being described as Proven Postseason Performers. George Springer, Jose Altuve, Joc Pederson; it seems to simply be common knowledge that they have some secret baseball skill they only activate come playoff time.

One thing that you could do, should you be so inclined, is to simply take people at their word. The world could use a little more magic in it, after all, and there being players who somehow see the ball better when it counts most is a really fun concept.

Sadly, I think they’re just a concept. To wit: take a look at the best hitters from the combined 2016-2017 postseason (among batters who have played in at least one postseason game since, for reasons that will become clear), minimum 25 plate appearances:

There are a lot of Astros and Dodgers here, which makes sense given the composition of those particular playoffs. Extend the list a bit more, and you’d get Christian Yelich, Max Muncy, and Francisco Lindor, three very good hitters. The list of good hitters in the playoffs looks suspiciously like a list of good hitters plus Orlando Arcia.

One quick note: I’m using wOBA here, but you could use OPS if you wanted to, or whatever measure of offensive value you prefer. You won’t find a metric that says David Freese wasn’t a good postseason hitter, or that George Springer’s .327/.352/.682 line wasn’t amazing, so the broad strokes will be the same regardless of what you choose.

If being a Proven Postseason Performer has any meaning, these hitters should continue to be great in subsequent years. Not in every case, of course: it’s baseball, which means that samples get messy and things you don’t expect happen. A list of mostly good hitters who have already performed in the playoffs seems like a good way to predict which hitters will do well in the future.

So long as we limit ourselves to a sample of one, the theory is foolproof. Here’s a stupid list, the top one hitter in the 2017-2018 playoffs plus his performance in the 2019 and 2020 playoffs, along with the number of plate appearances in the second sample:

Yep, Freese is great, we’ve solved it, everyone can head home. Sarcasm aside, Freese was awesome in a brief cameo in 2019 and then retired. That isn’t going to tell us much. Let’s expand the list to the top 15:

Huh. Springer was great, then average. Judge was phenomenal and then below average. Arcia turned back into Orlando Arcia. There are a few players who kept doing well, and a few who turned it on from an already impressive level, but there’s really not much to see here.

In total, these 15 best batters from the 2017-2018 playoffs have received 967 plate appearances in the subsequent two years. If they performed at the same level they did in 2017-2018, they would compile an aggregate .381 wOBA, an impressive mark. In other words, Freese would contribute eight plate appearances of .482 wOBA hitting, Springer 145 of .449, and so on.

How did they do in real life? They put together an aggregate .333 wOBA, better than average by a hair but hardly otherworldly. To use 2020 batters as an example, they hit like Paul Goldschmidt (.304/.417/.466) in the first sample and Willson Contreras (.243/.356/.407) in the second. Putting up a Goldschmidtian line in the playoffs will get you noticed. Being quietly competent, like Contreras’s 2020, simply won’t.

What a stupid metric, I can hear you saying. They were still above average! That’s true, but we’d expect this group of hitters to be better than average. From 2017 to 2018, and using the same weighting method as before, they hit for an aggregate .365 wOBA. In other words, they basically played like themselves in the playoffs.

This isn’t really evidence of anything. It’s only a few batters, over only a few years. So let’s kick it up a notch. Here are the top batters from 2014 to 2018, again among those who have played in the postseason since:

This is a group of the best playoff hitters over a five-year span. That’s as long as any “this guy hits in the playoffs” narrative, short of a hitting version of Clayton Kershaw. How’d they do in the subsequent two years?

Yup, pretty badly! Weighted by their ’19-’20 postseason plate appearances as we did above, we’d “expect” these hitters to compile a .396 wOBA based on their playoff past. Instead, they compiled a .316 wOBA, a below-average hitting line. Kyle Schwarber was postseason bulletproof until the Cubs got Marlin’ed this year. Matt Carpenter and Josh Donaldson were monsters until they weren’t.

While we’re here, let’s do the other side of the sample. How about the 15 worst hitters in the playoffs from 2014 to 2018?

By the weighted aggregate method, we’d “expect” those batters to put up a .235 wOBA in their ’19-’20 plate appearances. Instead, the aggregate was .305, hardly different than the production of the top 15.

The difference is actually even worse than that, though. I looked at regular season production in 2017 and 2018 to set a baseline for what we’d “expect” each group to produce. That aggregate came out to .364 for the set of great postseason hitters; it’s a list full of MVP candidates and good-hitting DH’s. The poor-performance group checked in at .335; still good hitters, but markedly worse.

In other words, if you came up with a “playoff clutch factor” by seeing how much better each group was than their regular season production, the first group was 30 points of wOBA better than expectation — amazingly clutch! In 2019 and 2020, they were then 48 points worse than expectation — sad times.

The group of playoff laggards was a whopping 100 points of wOBA worse than expectation from 2014 to 2018. What a bunch of bums! In 2019 and 2020, they were only 30 points worse than their regular season statistics would suggest, The playoffs are tough sledding overall, but the “bad” batters saw their production decrease by less than the “good” ones.

Is that some big surprise? Nope, not really. Statistics simply work that way; we all know that these sample sizes, none of which are overwhelmingly large, would produce some outperformers and underperformers even if everyone’s skill level were exactly the same. That’s simply the nature of baseball in small doses; heroes and goats are going to exist regardless of whether they’re actually great or terrible.

Again, you probably didn’t need to hear this. Watching baseball is enough to understand its randomness. Every single plate appearance is a challenge, whether it’s a great pitcher against a terrible batter or vice versa. You can’t take anything for granted; a player is only a goat until he’s a hero. It’s worth remembering, though, before this World Series starts: the playoffs are great, perhaps the best time all year to watch baseball. They aren’t immune to the central math of the game, however: in small samples, everyone is great and anyone can win.

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