A couple of months ago, I wrote an article about platoon options, and astute reader Tacocat pointed out that platoon hitters never actually realize their versus left-handed pitcher or versus right-handed pitcher splits that we frequently cite. Instead, platoon hitters start games with a platoon advantage, and then sometimes managers have to leave them in to face same-handed pitchers out of the bullpen.
Daily players use the same decision-making as actual managers. You can choose to start a platoon player because he is facing an opposite-handed starter, but that creates a chance that he could see a plate appearance versus a same-handed reliever later in the game. If you are relying on a split stat versus left-handed or right-handed pitchers to make that start/sit decision, then your platoon hitters will underperform your expectations on average.
Fortunately, we can do better. I started by trying to answer the simple question of how often hitters who start games with the platoon advantage actually see the platoon advantage in all of their plate appearances in those starts. With play-by-play data, that is pretty easy to answer. Since 2002, left-handed hitters have seen the platoon advantage in 82.9 percent of the plate appearances in starts in which the opposing starter was right-handed. Right-handed hitters have seen the platoon advantage in 50.7 percent of their plate appearances in starts in which the opposing starter was left-handed.
Those percentages provide a potential weighting to apply to hitter versus left-handed and versus right-handed splits, but I think they oversimplify the nature of platooning. Many hitters are good enough that they play pretty much every day, and obviously those hitters will sometimes start games in which the opposing starting pitcher provides them a platoon advantage. We shouldn’t expect those hitters to be removed in late-inning situations when same-handed relievers enter the game, so I suspected those percentages somewhat understated how often true platoon players faced opposite-handed pitchers in their platoon starts.
To solve that problem, I needed to answer a separate question of what constitutes a platoon hitter. To do so, I looked at the percentage of all starts hitters saw versus opposite-handed starting pitchers and attempted to find the logical boundaries between everyday players and platoon players. Here are the left-handed hitters from 2015 sorted from the highest to the lowest percentage of starts with the platoon advantage over the opposing starting pitcher to illustrate.
It isn’t completely cut and dried, but I see the transition for left-handed hitters happening around 89 percent. Just above that threshold are players like Alejandro De Aza, Ryan Howard, and Travis Snider who each had platoon partners I could (sort of) easily identify—Shane Victorino and Rusney Castillo, Darin Ruf, and Steve Pearce and Nolan Reimold. Meanwhile, just below the threshold are players like Kyle Schwarber and Adam LaRoche who generally played every day when they were healthy and on their rosters.
|Hitter||GS||Platoon Adv vs Starter|
|John Ryan Murphy||43||65.1%|
|Scott Van Slyke||53||60.4%|
|Melvin Upton Jr.||47||48.9%|
From the right side, I’m seriously impressed the Indians were able to start Ryan Raburn in 50 games without any of them having a right-handed starter. More on point, the right-handed threshold is around 45 percent, below players like Chris Denorfia (platooned with Chris Coghlan and Mike Baxter) and Rajai Davis (platooned with Anthony Gose) and above players like George Springer and Mike Napoli.
Next, I recalculated how often hitters who start games with the platoon advantage actually see the platoon advantage in all of their plate appearances in those starts using only hitters who exceeded those thresholds in 40 or more plate appearances each season. That added filter increased the left-handed platoon advantage to 84.9 percent (up 2.0 percent) and the right-handed platoon advantage to 52.6 percent (up 1.9 percent).
The next step will be to use those platoon percentages to project platoon hitters in their daily matchups, but I’ll leave that for next week because I’m tired and because I want to have a chance to read any feedback you may have for me.
Scott Spratt is a fantasy sports writer for FanGraphs and Pro Football Focus. He is a Sloan Sports Conference Research Paper Competition and FSWA award winner. Feel free to ask him questions on Twitter – @Scott_Spratt