Platooning a left-hander and a right-hander is a fairly common practice for major league teams, but utilizing platoon partners on your fantasy team isn’t the best way to take advantage of platoon splits. This may seem super obvious to you, but it’s better to use two lefties on separate teams who are used as platoon players as opposed to using two players who are platoon partners on the same team. In other words it’s better to go with Matt Joyce and Daniel Nava than it is to go with Nava and Jonny Gomes.
Again, this won’t be news to some of you, but I see people on message boards, Twitter, etc. discussing using platoon partners or worse, using a left-hander and a right-hander on separate teams to platoon in a roster slot. That latter idea is a bad one because there will be days when neither player has the platoon advantage. The left-hander figures to have it in about 2/3 of his games. Assuming you get 700 PA out of the spot you’re platooning, you’d get roughly 470 PA with the advantage from your left-hander (not accounting for bullpen substitutions). But a right-hander only has the platoon advantage in about 1/3 of his games. In the 230 PA where the left-hander doesn’t have the platoon advantage, you can only count on the right-hander having it a third of the time, aka roughly 75 PA. That adds up to 545 PA with the platoon advantage and 155 without it, which works out to about 35 games where you wouldn’t have a player in your platoon who actually has the platoon advantage.
As for using Gomes and Nava, that pair is projected by ZiPS to combine for 814 PA compared to Joyce and Nava who are projected to combine for 924 PA. Joyce had the platoon advantage in 88% of his plate appearances last year, and Nava had it in 74%. The odds of one of them having the platoon advantage on a given day is about 97%. That means that pair would have 895 with PA with the platoon advantage. Of the 814 PA Gomes and Nava will accumulate, not all will be with the platoon advantage, so Nava/Joyce will have the platoon advantage for a significant number of plate appearances more than Nava/Gomes will.
Additionally, Nava and Joyce will both have the platoon advantage on a given day about 65% of the time. This will obviously never happen for Nava and Gomes. There will also be days where Nava or Gomes will have a tough matchup, and you won’t have the option of sitting them against someone like David Price. But with Nava and Joyce both having the platoon advantage about two thirds of the time, you’ll be able to avoid some of the bad matchups. Nava and Gomes will also obviously have the same off days, but Nava and Joyce won’t. That means there are potentially 181 days where one of your platoon guys has a game as opposed to just 162 if you use teammates.
Just to get an idea of what Nava/Joyce could give you, I pulled their game logs from last year. I eliminated all games in which either player didn’t have at least three plate appearances. On days where both players had 3+ PA, I alternated which player’s stats to use for that day. I added those selections to the stats from days where only one of the players played. That gave me the following line: 638 PA, .292, 15 HR, 5 SB, 89 R, 73 RBI. This is probably a conservative estimate because there would have been a few days here and there where neither player got to three PA but did get to the plate one or two times. And I didn’t have the ability to choose the guy who had the better matchup on days they both played nor did I have the ability to assure that I didn’t include stats from a player who didn’t have a platoon advantage on a day they both played.
When I run those numbers through my valuation system, a Nava/Joyce platoon would be a minimum of a top 40 outfielder assuming my estimate is on the low end. If the two combined for something like 19 HR, 93 R and 76 RBI, the pair would be as good as a top 35, borderline top 30 outfielder. In terms of auction dollars, the pair would give you $10-12 worth of production. Both guys are essentially going undrafted in shallow mixed leages on ESPN.com and could probably be had for a combined $2 and probably wouldn’t cost more than a combined $4-5 in any shallow league.
Platooning isn’t always a great idea if you’ve got short benches. Standard ESPN leagues only have three bench slots, and it’s tough to commit one of those to a platoon when those spots have to be used to stream starters or to hold injured players who haven’t been put on the DL. I often like to use those extra slots for elite middle relievers to help with ratios. But if your league has five bench spots or more, going with two left-handers for one slot is a good idea.
Identifying left-handers to use is fairly simple. I would just go the leaderboards here on the site, choose the ‘vs. R’ split and then sort by wRC+ or wOBA. Then cross reference that with the ADP or auction values from the website you’ll be using to draft. Just pick out two guys with an above average wRC+ against right-handers, make sure they’re left-handed, make sure you can get them cheap, and there are your platoon mates.