Did a Misunderstanding of Platoon Splits Cost the Baltimore Orioles the American League Wild Card Game?

Buck Showalter left stud Baltimore Orioles' reliever Zach Britton in the bullpen last night in favor of Ubaldo Jimenez, and it cost the Orioles the game. Could this mistake have been prevented by looking at platoon splits?

I can personally guarantee you that Baltimore Orioles manager Buck Showalter knows more about baseball than you and me combined. He's a three-time American League Manager of the Year, and he has been working in baseball in some capacity since he broke into the minors all the way back in 1977.

That doesn't make what happened last night any less befuddling.

With the wild card game between Showalter's Orioles and the Toronto Blue Jays tied at 2-2 in the bottom of the 11th, Showalter handed the ball to righty Ubaldo Jimenez in relief. Reliever Zach Britton -- who has generated buzz as potential Cy Young candidate -- sat in the bullpen, waiting for his shot in the win-or-go-home matchup.

He never got it.

With one blast, Edwin Encarnacion sent the Blue Jays on to the division series, and Showalter, Jimenez, and Britton went home.

If you were looking for a rational explanation of why Showalter used Jimenez -- who lost his job as a starter early in the season and spent the rest of the year bouncing back and forth between the rotation and the bullpen -- you likely didn't get it.

It doesn't matter how well Jimenez was pitching; in a relief outing, Britton is always going to be the superior option. You don't stumble your way into a 1.74 skill-interactive ERA (SIERA), the third-best mark in all of baseball. These explanations really leave you digging for more info on why Showalter made such a confuddling decision.

There is one big difference between Jimenez and Britton that would seem to work in Jimenez's favor against the Blue Jays: Jimenez is right-handed while Britton is a lefty.

The Blue Jays have made a name for themselves by blasting southpaws the past two years, and you generally expect a right-handed pitcher to fare better against their righty-heavy lineup. Could that have played into Showalter's preference of Jimenez?

There's only one problem with this line of thinking when it comes to these two specific pitchers. They aren't your average cookies, and their platoon splits would throw this line of thought right out the window.

A Pair of Reverse-Splits Hurlers

To best get a feel for when you should deploy a pitcher based on the handedness of the opponent, you should be focusing on their platoon splits for their strikeout rate, walk rate, and hard-hit rate. If batters of one handedness fare demonstrably better against that pitcher, you should try to avoid such situations. And while it's fair to simply assume a righty will fare better against same-handed batters, that's not the case for Jimenez.

Check out Jimenez's splits from this season against batters on both sides of the dish. This should make it fairly clear that you don't want him facing guys like Encarnacion, Josh Donaldson, and Jose Bautista.

Versus Handedness Strikeout Rate Walk Rate Hard-Hit Rate
Right-Handed Batter 17.8% 11.1% 30.8%
Left-Handed Batter 22.0% 11.6% 31.1%

While Jimenez's numbers were comparable in both walk rate and hard-hit rate, his strikeout rate tumbled when there was a righty at the dish. Fewer strikeouts means more balls in play, and that leads to more potential calamity for the pitcher.

The interesting thing about Jimenez is that this didn't shine through in his more traditional stats this year. He allowed a .378 wOBA to left-handed batters compared to .308 against righties, meaning you'd think he'd be safer against righties. Those rates don't stabilize as quickly as plate-discipline and batted-ball stats, meaning if there's a difference between the two, we should give preference to the strikeout rate, walk rate, and hard-hit rate.

None of this would matter, though, if Britton struggled against righties. He is, after all, left-handed, so we might expect his performance to lag a bit when an opposite-handed batter is at the dish. Again, though, these assumptions would be flat wrong.

Versus Handedness Strikeout Rate Walk Rate Hard-Hit Rate
Right-Handed Batter 29.9% 6.7% 16.3%
Left-Handed Batter 26.7% 8.3% 10.3%

Among pitchers who threw at least 50 innings, nobody in baseball allowed a lower hard-hit rate to right-handed batters than Britton. In fact, he was the only guy below 20.0% in that category, so it wasn't even close. Even though he's a left-handed pitcher, there aren't many guys in the league better at shutting down righties than Britton.

Again, Showalter's a smart guy, so it's entirely possible that he knew all of this going in. But when it comes to the Orioles, they have shown in the past that they are painfully aware of how well the Blue Jays bang lefties.

Last year, Wei-Yin Chen had a 2.89 ERA through his first 13 starts of the season, and he had just hurled eight shutout innings with nine strikeouts in his most recent outing. The Orioles promptly demoted him to High-A ball the next day. Why would they do that?

The team cited "general soreness" and said he would be back after his required 10 days in the minors. Chen, though, felt fine.

It turns out the team had a date with the Blue Jays just around the corner, and Chen was scheduled to face them. He is left-handed. Showalter never mentioned this as a reason for Chen's demotion, but given Chen's effectiveness up to that point and his tweets about being in good health, the timing was curious to say the least.

So, is this fear of throwing a left-handed pitcher against the Blue Jays what drove Showalter to use Jimenez over Britton? We may never know. But given the Orioles' history and the lack of other quality explanations, you have to wonder if a better understanding of the individual pitchers' platoon splits may have helped extend the game and send the Orioles onto the next round.