Collette Calls: The Dangers of Lefty Platoon Splits

Collette Calls: The Dangers of Lefty Platoon Splits

This article is part of our Collette Calls series.

Every season, we are surprised by a player who does something out of line with his career numbers. Brandon Phillips, after six seasons of declining steals, stole 23 bases at age 34. Norm Cash was a .270 career hitter as he began the 1961 season, a season in which he hit .361. Joe Mauer hit 28 home runs over his first three seasons in the major leagues and then hit 28 alone in his sixth season. He has never again hit as many as 12 home runs in a season.

In April, I explained why I went after lefty-hitting outfielders. In short, I find them to be undervalued because they either struggle against lefty pitchers or their playing time is reduced because their managers do not allow the player to see the field when a southpaw is on the mound. You can accept the loss in playing time because it helps the player's batting average (and likely OBP) from tanking by being overexposed to their weakness. Sometimes, the manager alters those plans and lets the batter get more exposure to lefties if the hitter's defense is tough to take off the field or the hitter begins to show more success. A good example of this from this past season would be Josh Reddick.

2012 239 5 23 .237 .277 .473 .261
2013 145 12 18 .200 .299 .368 .202
2014 108 6 19 .222 .280 .253 .282
2015 149 9 13 .222 .291 .363 .234
2016 104 7 18 .155 .212 .155 .192
2017 101 7 19 .315 .360 .402 .384

Oakland let him play quite a bit against lefties early on and then curtailed things a bit in recent seasons despite sub-optimal results. Reddick still made contact against lefties, but the amount of damage he did against them, outside of that early success in 2012, just was not there. Reddick's defense is good enough to keep him in the field on a regular basis, but look at the numbers Reddick has amassed against solely righties:

2012 434 10 22 .245 .320 .457 .273
2013 296 10 20 .238 .311 .385 .280
2014 288 7 15 .280 .330 .519 .291
2015 433 8 10 .289 .347 .478 .292
2016 335 10 11 .322 .386 .485 .341
2017 439 8 12 .314 .363 .504 .329

Reddick was quite productive from 2014-16 against righties while steadily declining against lefties, which dragged down his overall numbers. That changed in 2017 with his newfound effectiveness against lefties. The quandary we are in now is figuring out which is real: the 101 successful plate appearances against lefties in 2017 or the dreadful 745 plate appearances against lefties from earlier seasons?

The research from the FanGraphs library has this to say about splits:

You learn a lot more about a player in 400 PA than you do in 40. This is true over a full season or within a split. You need to pay attention to the sample size for each part of the split and not the overall sample size. A platoon split over 300 total PA won't tell you very much because you're likely only looking at 75-100 PA against lefties, which is simply not enough to tell you much about the hitter. You also have to be careful about using more and more seasons to increase your sample size because player talent changes and data from five years ago isn't as informative as data from this year.
The tl;dr (too long; didn't read) explanation there is that you must honor the sample size while understanding a player isn't the same guy in Year 1 as he may be in Year 6.

In the case of Reddick, his performance against lefties had been worsening in recent years before this year's surprise turnaround. This whole scenario even played out in the World Series as Reddick was left in the lineup to face both lefty starters and even LOOGY's such as Tony Watson even though Cameron Maybin was waiting on the bench. Reddick's defense is so valued that A.J. Hinch left him in there, regardless of matchup, and he did not do very well this postseason because of it.

Using Reddick as our model, let's look at some of the other lefty hitters who did serious damage against lefty pitchers in 2017 to see if said player could be in for more playing time in 2018 or if this year was an aberration compared to earlier efforts. We'll begin with the lefty who led all lefties in batting average against fellow southpaws.

Gerardo Parra

2012 95 2 21 .256 .283 .349 .303
2013 200 9 17 .198 .276 .226 .243
2014 112 11 24 .206 .306 .247 .275
2015 117 5 16 .238 .296 .362 .262
2016 100 2 19 .258 .273 .361 .312
2017 106 4 18 .347 .377 .429 .412

Parra is similar to Reddick in that both are valued for their defense, and Parra was left in the lineup every day while in Arizona and it wasn't until he went to Milwaukee and then Baltimore that he started sitting against southpaws. Last year, he missed some time with a quad strain in summer, but when he did hit against lefties, he did surprisingly well. Then again, playing in expansive Coors Field certainly helps, and Parra did slap his way to a .382 average at home against lefties as 16 of his 21 hits in 55 at-bats were singles. The .302 against lefties on the road wasn't bad either, but it only involved a single extra-base hit. 2017 looks like quite the outlier against what Parra has done in previous seasons, and even Coors Field can't allow that type of inflated BABIP for too much longer.

Jon Jay

2012 148 10 12 .281 .361 .336 .327
2013 137 10 19 .220 .306 .314 .264
2014 94 4 22 .375 .404 .455 .485
2015 44 9 14 .158 .256 .158 .188
2016 120 8 20 .308 .378 .374 .398
2017 101 12 17 .318 .410 .341 .391

Speaking of slappies, Jay turned himself into a decent, little NL-Only play this year for runs and batting average and now has back-to-back effective seasons against lefties. In fact, if we remove the 2015 line, he's been mostly effective against lefties throughout his career. Jay has a ceiling of effectiveness due to his lack of power and speed, but he's cheap runs and batting average help in single leagues and could end up with more playing time in 2018 leading off with Chicago assuming it offers him arbitration. That is no guarantee for a 1.6-win player who is due to make at least $10M in 2018.

Corey Dickerson

2013 40 10 25 .194 .275 .306 .240
2014 98 7 27 .253 .306 .418 .323
2015 59 5 32 .268 .305 .357 .405
2016 113 4 31 .241 .274 .315 .338
2017 165 4 26 .308 .339 .481 .405

Last year, by far, was Dickerson's most productive season against lefties. The Rockies rarely gave him chances to do it and the Rays have left him in there as they needed his power in the lineup. The 2017 numbers look like the outlier for him, and while his
overall production slumped as the season wore on, his numbers against lefties mostly held up. The 2016 numbers give us a more realistic expectation of what we can expect from Dickerson in 2018 as the Rays are once again likely to leave him in there as much as he can play in 2018.

Shin-Soo Choo

2012 242 12 25 .199 .318 .286 .271
2013 221 11 20 .215 .347 .265 .283
2014 161 9 31 .236 .323 .350 .330
2015 248 10 22 .237 .333 .374 .286
2016 56 13 18 .304 .429 .587 .313
2017 146 14 16 .287 .400 .352 .351

Choo is an interesting case because his defense does not deserve extra playing time, but his plate skills do. His OBP the last six years was .373, .423, .340, .375, .357 and .357. His defense is bad enough where he needs to be a full-time DH, but he got 77 games in the outfield in 2017. The issue is whether to believe the recent 200 plate appearances against lefties or the previous four years of futility against them. He has an established ability to earn his walks against lefties throughout the years, but it has only been recently that he has been able to do anything else but walk against them. Last year, it was mostly a singles game for him as 29 of his 35 hits against lefties were singles and just one went over the fence.

Oddly enough, Choo's recent success against lefties is being offset by his struggles against right-handed pitching. Whereas he has made a career of raking righties, his numbers the last two seasons against righties are just .245/.341/.417. Frankly, it is tough to explain a lefty struggling this much against righties after doing so well throughout the rest of his career against them.

I would be remiss if I did not look into the other side of this coin – the lefties that lost all abilities to hit fellow lefties in 2017. No batter personified this struggle more than a Texas Ranger.

Rougned Odor

2014 119 5 22 .248 .305 .321 .309
2015 170 4 18 .266 .320 .461 .300
2016 169 5 21 .269 .308 .455 .302
2017 170 3 25 .145 .200 .252 .161

Odor struggled against all types of pitching in 2017 and still managed to hit 30 homers. His free-swinging ways as he attempts to hit every ball in the air have not worked out as well for him as it has for others. The issues against lefties did not improve as the season went on, but we also cannot fall for the recency bias of 2017 and ignore his league-average output against lefties the previous three seasons. I'm not suggesting running out and dropping $20-plus on him in drafts, but I am not running away from him in drafts either.

Matt Carpenter

2012 105 3 23 .265 .305 .480 .300
2013 222 7 13 .294 .353 .467 .321
2014 217 12 19 .262 .361 .361 .324
2015 211 11 26 .228 .322 .429 .276
2016 174 13 20 .270 .363 .446 .318
2017 137 16 23 .202 .343 .321 .256

2017 was the first season Carpenter was below league average against southpaws, and it came on the heels of one of his best seasons against them. After three consecutive seasons of hitting .271-.272 overall, he hit a career-low .241, and the struggles against lefties were a contributing factor to that problem. A big reason why he struggled is that he was dealing with right shoulder problems most of the season, a pain which Carpenter described as a "sharp pain on pretty much every throw and most swings." Despite the shoulder trouble, Carpenter eclipsed 20 homers for a third consecutive season since he revamped his swing, but hit .451 slugging percentage was the second lowest of his six-year career, which is to be expected when a shoulder injury prevents a pain-free extension to a swing.

We have to be aware of platoon splits while not falling into the trap of recency bias. Hitters like Odor and Carpenter disappointed last year due to unforeseen struggles against lefties, but that should not deter you from rostering them in 2018. Conversely, hitters like Reddick, Dickerson, Choo and Parra may have a tough time repeating the success.

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Jason Collette
Jason has been helping fantasy owners since 1999, and here at Rotowire since 2011. You can hear Jason weekly on many of the Sirius/XM Fantasy channel offerings throughout the season as well as on the Sleeper and the Bust podcast every Sunday. A ten-time FSWA finalist, Jason won the FSWA's Fantasy Baseball Writer of the Year award in 2013 and the Baseball Series of the Year award in 2018 for Collette Calls, as is the 2023 AL LABR champion. Jason manages his social media presence at
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