Realized Platoon Rates
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 |
| Ryan Raburn | 50 | 100.0% |
| Franklin Gutierrez | 42 | 78.6% |
| Shane Victorino | 50 | 70.0% |
| Jake Smolinski | 50 | 68.0% |
| Brandon Guyer | 79 | 67.1% |
| John Ryan Murphy | 43 | 65.1% |
| Clint Barmes | 51 | 64.7% |
| Mike Aviles | 79 | 64.6% |
| Josh Phegley | 62 | 64.5% |
| A.J. Ellis | 55 | 63.6% |
| Chris Young | 77 | 61.0% |
| Tim Beckham | 51 | 60.8% |
| Scott Van Slyke | 53 | 60.4% |
| Jonny Gomes | 55 | 58.2% |
| Nolan Reimold | 45 | 57.8% |
| Wilin Rosario | 54 | 55.6% |
| Darin Ruf | 62 | 54.8% |
| Shane Robinson | 48 | 54.2% |
| Gordon Beckham | 50 | 54.0% |
| Jeff Francoeur | 71 | 53.5% |
| Danny Valencia | 85 | 52.9% |
| Kiké Hernandez | 51 | 52.9% |
| Jake Marisnick | 101 | 52.5% |
| Paulo Orlando | 63 | 52.4% |
| Chris Carter | 112 | 50.9% |
| Rajai Davis | 73 | 50.7% |
| Joey Butler | 61 | 49.2% |
| Melvin Upton Jr. | 47 | 48.9% |
| Chris Denorfia | 45 | 48.9% |
| Hernan Perez | 66 | 48.5% |
| Steve Pearce | 79 | 46.8% |
| Alex Guerrero | 49 | 44.9% |
| George Springer | 101 | 44.6% |
| Peter Bourjos | 41 | 43.9% |
| Aaron Hill | 73 | 43.8% |
| Mike Napoli | 115 | 43.5% |
| Domingo Santana | 44 | 43.2% |
| Delino Deshields | 110 | 42.7% |
| Chris Johnson | 61 | 42.6% |
| Justin Maxwell | 59 | 42.4% |
| Mark Canha | 108 | 41.7% |
| Delmon Young | 41 | 41.5% |
| Kelby Tomlinson | 46 | 41.3% |
| Robinson Chirinos | 73 | 41.1% |
| Mark Trumbo | 132 | 40.9% |
| Evan Gattis | 147 | 40.8% |
| Michael Morse | 57 | 40.4% |
| Elvis Andrus | 159 | 40.3% |
| Jake Elmore | 40 | 40.0% |
| Adrian Beltre | 143 | 39.9% |
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
It would be cool if steamer would provide split projections. Then we could actually apply this article.
Solid article. I will be very interested in the follow up piece. As a Pirates fan the Pedro Alvarez and G Polanco names were interesting last year. Pedro was lousy against Lefties, to my eye anyways. Polanco sat out to start the games they faced LHP for the first…maybe 3 months of the season? But then Hurdle played him more regularly against LHP. I guess my point is that it will always be tough to project how coaches manage in game especially young players, and maybe even more specifically young Lefty batters versus LHP. (since their same handedness disadvantage is generally the worst and yet their potential improvement is untapped.)
This is an admirable job of quantifying AB, but perhaps not all AB are created equal. If its a high leverage situation later in the game it seems far more likely that a platoon hitter would find himself facing a same sided relief specialist, resulting in either total loss of the AB in an RBI situation if he is pinch hit for, or diminished chances of success.
This is an ironic argument to make given that on the same day that your article was posted the one just above it was titled “Leverage is a Myth” or something to that effect.
Did you read that post? It’s not about THAT kind of leverage.
I’d like to see not just percentage of ABs with the platoon advantage, but how many ABs to expect total. That way we could estimate “Seth Smith is likely to have 4 ABs (or whatever the number is) today, and therefore should be expected to have 3.4 AB vs RHP and 0.6 vs LHP”.
Then we could center a regressed split around the Steamer projection to get a projectiom of vs RHP and vs LHP split and use it to get projections for a game with a lefty starter or a righty starter. Display these numbers as either per 162 games (to demonstrate the type of hitter the guy is vs RHP or vs LHP) or per 100-110 games (to demonstrate what numbers you could expect if you only start the guy when he has the platoon advantage)
Is there benefit in this analysis over the “vs LH Starter” split at baseball-reference?