Wait, That Guy Isn’t a Lefty?

A friend was asking a question about matchups in the coming month, and was talking about lefties and how Houston has done against lefties and maybe he should start A.J. Griffin against them and so on. I was playing along, pointing out that maybe it wasn’t a great matchup because Houston has a good lineup and they’re in a park that’s good for offense and all that. I didn’t even blink.

Of course, Griffin is a righty. No idea why we both thought he was a lefty, but we’re not alone. A quick Twitter poll — results below! — revealed Griffin as a top contender for “righty we most think is a lefty.”

Unfortunately, none of us know why we mentally mistake hands on some players. Or at least, we don’t have a quick answer to that question, other than vague references to arsenal (“crafty”), temperament (“different personalities”), or television time (“I don’t see them much”). Most responses to the poll included an “I don’t know why” of some sort.

Still, it’s something we do. And it’s sort of fascinating, because lefty starters do actually do things a little differently than righty starters — things we can actually define objectively. Which means we can apply the statistical definition of a lefty starter to the righty-starter population. And we can answer this question with stats!

So… which righty really acts the most like a lefty? Which righty is the most lefty-like? Turns out, it’s not Griffin, but the wisdom of the crowd was not far off, really.

Let’s define lefty starters against righty starters. I’ve done most of the work from a different vantage point before, so here’s that work re-summarized for the benefit of our question today.

Lefty starters:

Using that rubric, we can already narrow the pool of right-handed starters to our main contenders for Secret Lefties.

Just by asking which pitchers throw a ton of changeups, don’t have a ton of velocity, and prefer four-seamers to sinkers, we have an interesting collection of pitchers.

But! Mike Fiers throws a split-finger change. Perhaps because of the mechanics of the pitch, it’s not the favorite of lefty starters. Jorge de la Rosa and now Ariel Miranda are the only starters on the PITCHf/x leaderboard who are listed as throwing one regularly, and though Tony Sipp throws one, there aren’t a ton of relievers either. Let’s take Fiers out.

Marco Estrada really prefers his four-seamer to his sinker. To the point that he doesn’t throw a sinker at all. That seems weird. A lefty without a sinker? Let’s take Estrada out.

We’re still left without an obvious way to to cull the rest of the list. Except! Lefties are thought to “sling” the ball more across their body, with lower release points. The average movement by pitch type for lefties and righties is different. And there’s a pattern to their difference: lefties get more horizontal movement, and less vertical movement, than their righty counterparts.

In particular, lefty changeups and sinkers are more tilt than drop. Now let’s revisit our group of pitchers, and sort for sinker fade. It all comes together.

By this definition, Dan Straily has too much drop on his changeup to be our secret lefty. James Shields and Jered Weaver not enough fade, maybe. Plus, we’ve seen a lot of Shields and Weaver over the years, no?

Chase Anderson was my secrete favorite going into this exercise. Turns out, the Twitter and Slack populations liked him as a lefty, too. Here are the righties that received more than two “That Guy’s Not a Lefty?” votes from the crowd.

And they were right! The crowd lined up with our numbers in a lot of ways. Along with Jeremy Hellickson, Anderson has the arsenal most like a lefty’s in baseball.

It’s okay if you get it wrong in the future, then. You’ll probably get it right eventually, though it’s worth pointing out that Max Scherzer, Greg Maddux, and Tim Lincecum each got a vote as screw lefty. Sometimes those crossed synapses harden into place. Sometimes a righty is a lefty forever in your brain, no matter what he throws.