The Stereotype of Lefty-Righty Splits: Mostly True

There is a perception about platoon splits that reminds me of lots of social stereotypes. The thing about stereotypes is that they exist for a reason: because they are usually true. But, in the cases where they are not true, they can be dangerous and damaging.

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Rather than risk bringing up some very touchy subjects that would upset half my readers, just take a minute and think about some of the stereotypes you might believe, maybe about politics, religion, race, etc. Chances are you’ve thought of at least a couple beliefs you hold which are probably true in the majority of cases, but there are always going to be outliers. There are people that, for whatever reason, completely break the mold.

As is the case with social stereotypes, the same is true with pitchers and their lefty-righty splits. The conventional wisdom that pitchers perform worse against opposite-handed hitters is conventional wisdom for a reason: it is usually true. If you are shortcutting your way through roster construction without time to dig into all the metrics, I would tell you to only start left-handed hitters against right-handed pitchers and vice-versa.

Before we start looking at outliers, let me show some data from 2014 that confirms the stereotype of why you should play hitters against opposite-handed pitchers.

2014 MLB right-handed hitters versus right-handed pitchers: .247 average, 1 home run every 39 at bats
2014 MLB left-handed hitters versus left-handed pitchers: .240 average, 1 home run every 55 at bats
2014 MLB right-handed hitters versus left-handed pitchers: .260 average, 1 home run every 36 at bats
2014 MLB left-handed hitters versus right-handed pitchers: .254 average, 1 home run every 40 at bats

This type of data confirms the notion of targeting hitters against opposite-handed pitchers. Both righties and lefties have higher batting averages against opposite-handed pitchers while left-handed batters generate most of their power against right-handed pitching.

It is important to note that handedness splits need a large sample size to become useful. Especially with left-handed pitchers against left-handed hitters, there are not typically enough at bats per season to draw a meaningful conclusion. The longer you see a trend, the more likely it is to be real. I like to see at least two full seasons of data when possible.

Going a step beyond lefty versus righty and righty versus lefty, there are some pitchers that develop a long enough track record to be known as “reverse-splits” players, meaning they perform better against hitters of the same handedness. These would be the exceptions to the stereotype. And while this is useful information, it is still not what is going to separate you from the crowd in DFS. The real useful data that can give you a big edge, especially in tournaments, is breaking down platoon splits by pitch type.
If we take what we’ve learned about strikeout and walk rates, ground ball and fly ball rates, and finding home runs from fly balls, we can next break down each of those stats by handedness to find even further advantages. Let’s look at some real-life examples of splits that don’t match conventional thinking;

Jeff Locke, Left-Handed Starter

2013 vs. LHB: 11.5 K%, 10.3 BB%, 62.2 GB%, 19.3 FB%
2013 vs. RHB: 19.4 K%, 12.3 BB%, 50.3 GB%, 27.9 FB%

2014 vs. LHB: 10.1 K%, 7.6 BB%, 59.8 GB%, 26.1 FB%
2014 vs. RHB: 18.0 K%, 7.2 BB%, 47.7 GB%, 30.6 FB%

This shows a clear difference in approach from Locke in right-handed batters versus left-handed batters. With the low strikeout rate and high ground-ball rate to left-handed batters, he is clearly intentionally allowing left-handed batters to put the ball in play but keeping it on the ground, trusting his defense behind him. Against right-handed batters, his approach changes, and he is trying to strike batters out at the expense of ground balls.

It looks to me like he is afraid of right-handers hitting him hard, so he is trying to strike them out but allowing more fly balls, which should result in more extra-base hits. The fly ball numbers from Locke are still low enough that you wouldn’t stack against him heavily in tournaments, but could get an edge from one or two power hitting right-handers.

The actual results from 2013 to 2014 show that Locke allowed one home run for every 94 left-handed batters and one home run for every 41 right-handed batters. But for base hits, he allowed a hit per 4.7 left-handed batters and a hit per 4.6 right-handed batters. He had a very fortunate .190 BABIP versus left-handed batters in 2014. If that evened out, the hits would have been even more strongly tilted in favor of left-handed batters.

I hope you can see that this is very useful DFS data. You would never consider playing a left-handed batter in a tournament against Locke as there is no home-run upside. But in a cash game, with the very low strikeout rate, a high-contact, high-BABIP left-handed hitter has a good chance of reaching base against Locke.

Josh Collmenter, Right-Handed Starter

2013 vs. LHB: 21.9 K%, 8.6 BB%, 36.1 GB%, 44.3 FB%
2013 vs. RHB: 22.3 K%, 8.6 BB%, 30.5 GB%, 48.3 FB%

2014 vs. LHB: 12.6 K%, 4.7 BB%, 46.4 GB%, 31.3 FB%
2014 vs. RHB: 19.4 K%, 6.2 BB%, 30.2 GB%, 49.8 FB%

Collmenter has the reputation of being a fly ball pitcher, which he is. But, if all the information you had was that he is a fly ball pitcher pitching in a home-run-friendly park in Arizona, you would likely load up left-handed bats against him to catch a platoon advantage. But a deeper look into the numbers shows that he is only a moderate fly ball pitcher against lefties but a heavy fly ball pitcher against right-handed batters. In a tournament, you would pass on the lefty-righty matchups and look for power-hitting right-handers against Collmenter.

Every stat we’ve gone through in the course can and should be checked against the handedness of the pitcher and the hitter. In the case of Collmenter, it is useful information to begin with that he allows a high fly ball percentage to right-handed hitters, but to take advantage of that, you need also need to find right-handed hitters who have that same tendency.

DFS Takeaways

The common perception of right versus left and left versus right matchups is correct, but not in every case. You can gain an edge over your competition by looking into each pitching metric separately by handedness. When you find an outlier, that is a good place to separate your lineup from the crowd in DFS.

About the Author

CheeseIsGood
Dave Potts (CheeseIsGood)

One of the preeminent baseball minds in all of fantasy, Dave Potts (aka CheeseIsGood) has won contests at the highest levels of both season-long and DFS. He is a 2x winner of a $1,000,000 1st-place prize in DFS; having won the 2014 FanDuel baseball Live Final and following that up by taking down a DraftKings Milly Maker Tournament in 2015. In addition, he’s won the Main Event championship in the National Fantasy Baseball Championship and the NFBC Platinum League, which is the highest buy-in entry league. His consistent success in the NFBC tournaments earned him a prestigious spot in their Hall of Fame. Dave can also strum a mean guitar while carrying a tune, and if you’re lucky, you’ll see him do so on one of his MLB Crunch Time appearances. Follow Dave on Twitter – @DavePotts2