The Saber's Edge: On the Upswing

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Updated on April 8, 2015 4:32PM EST

Everyone is looking for that small advantage in fantasy baseball that will put their team over the top. Hitter splits against certain pitcher types is one such advantage to exploit. While it is common to know if a pitcher mainly allows fly balls or ground balls, the batted-ball nature of hitters is rarely used in any hitter analysis. It should be, though. It is a great tie-breaker when deciding between two players in a daily lineup game.

To start with, here are some details on why a hitter will do better against certain types of pitchers and their pitch trajectories. The key comes down to swing plane. Dan Farnsworth at the Hardball Times describes how this works.

Baseball Prospectus recently spotlighted a 2011 article by Matt Lentzner, in which he used PITCHf/x data to explore different aspects of pitch movement. He runs more numbers than I care to repeat here, showing a spectrum of pitches crossing the plate on a 4° decline for a shoulder-height Justin Verlander fastball down to 12° for a knee-high Adam Wainwright curveball. In an interesting graph from the piece, he showed the lowest whiff rate was present on pitches that crossed the plate on a 7° decline, suggesting the average major league hitter swings on something like a 7° incline. Ted Williams advocated this approach in his book The Science of Hitting many years ago:

This is the same reasoning that likely explains why flyball hitters do better against ground-ball pitchers than ground-ball hitters do.

This is the same reasoning that likely explains why flyball hitters do better against ground-ball pitchers than ground-ball hitters do. A ground-ball pitcher tends to throw pitches with more negative vertical movement. The correlation between pitcher ground-ball percentage and average vertical movement on fastballs (PITCHf/x data) is slight but appreciable (R-squared = .14). Flyball hitters tend to swing on a sharper uphill plane, matching the steeper downhill plane of ground-ball pitchers. This results in more true contact and driving through the ball on the same level, producing more hard line drives and well-hit fly balls.

And the work was continued with a recent article by Shane Tourtellotte, also at the Hardball Times.

With two fly-ballers facing each other, the high angles they're both seeking could often add up to pop-ups, easy plays for fielders. With two ground-ballers, added downward trajectories could turn a sharp two-hopper through the infield into a little dubber the pitcher easily scoops up. And when one type faces another, they may strike a balance.
Between grounders and flies sits the zone of the line drive, well and away the most productive of the three main classifications of batted balls. If one players wants a fly and the other a grounder, a stalemate between their tendencies might produce a bounty of liners. This could go a long way to explaining why the opposite trajectory platoon is better for hitters than a same-type platoon.
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Despite that narrowness, we do see some solid conclusions. One is even the one I was hoping for: opposite trajectory platoons produce an elevated line-drive rate that helps batters perform better than against same trajectory pitchers

With the why out of the way, now it is time to move onto finding players who have this advantage. Easier said than done. For years, the only place this information was found was at Baseball-reference.com on each player's Splits page.

From watching Mike Moustakas play for the last few seasons, he has a huge upper cut in his swing. His bat is more likely to make contact with pitches with a downward/ground-ball trajectory. This is definitely the case as he has career .818 OPS against ground-ball pitchers and .632 OPS against flyball pitchers. This advantage makes Moustakas a must start against such pitchers as Twins right-handed Kyle Gibson (53.4 GB%). Moustakas has about a league average lefty-righty platoon split with a 100-point advantage in OPS against right-handed pitchers. His big advantage comes with the 200-point advantage against ground-ball pitchers. In just eight battles between the two, Moustakas is 3-for-7 with two doubles and a walk. Not a huge sample, but he has feasted on ground-ball pitchers. While no longer in the AL Central, Justin Masterson (58.0 GB%) pitched to Moustakas 23 times with Moustakas posting a 1.131 OPS. Moustakas, on the other hand, has only posted a .227 AVG against the Twins Phil Hughes (34.0 GB%), who is an extreme flyball pitcher.

Fantasy owners can easily find pitcher ground-ball rates, but a person would need to go to each hitter's page at B-Ref to get the batter splits. I have decided to do the work for you. I collected the three-year values (2012-2014) for 99 percent of all hitters (removed those in extremely small samples) who saw action in 2014. For continuity of information with B-Ref, I divided the ground-ball nature of pitchers into three groups by ground-ball percentage (GB%). I only use GB% instead of GB/FB ratio and FB% so I only have one value to reference. The ground-ball pitchers had a GB% greater than 48 percent, flyball pitchers had a rate less than 40 percent, and the middle group is between the two values. Here is a link to the values. Additionally, here are the top 10 regulars who see the biggest difference in OPS when facing high and low ground-ball pitchers.

Better Against High GB% Pitchers
(Difference between High GB% OPS and Low GB% OPS)

Carlos Gomez	+.224
Chris Carter	+.218
Jayson Werth	+.179
Mike Napoli	+.177
Todd Frazier	+.161
Pablo Sandoval	+.152
Josh Reddick	+.150
Justin Morneau	+.145
Matt Wieters	+.140
Darwin Barney	+.137

Better Against Low GB% Pitchers
(Difference between High GB% OPS and Low GB% OPS)

Carlos Santana	-.180
Mitch Moreland	-.182
Mike Morse	-.193
Mark Teixeira	-.208
J.D. Martinez	-.208
Yunel Escobar	-.223
Billy Butler	-.235
Garrett Jones	-.271
Adam LaRoche	-.278
Ryan Howard	-.299

In most cases, owners will take the better overall players like Carlos Gomez. But say they are in a league and need to decide between two right-handed hitters like Mike Napoli and Billy Butler. Looking to see if Butler is a facing a flyball pitcher while Napoli is facing a ground-ball pitcher could easily be the determining factor on whom to play. Small advantages like these add up over a season.

Now, how to make the data easy to use. I would recommending going though your rosters and finding out which hitters have this platoon advantage. Then find that day's starter (three-year pitcher ground-ball rates are on second tab of the linked document). It is not the easiest process, and I believe if it was easier, more people would be taking advantage of these players. Once an advantage becomes easier, everyone will begin to use it and it is no longer an advantage.

I believe hitter batted-ball splits are the most underutilized advantages in fantasy baseball. The information is not easily obtained and takes a bit of work to integrate it into setting daily lineups. In a game where a season can come down to just a small differences in stats, the use of this information can't be understated. As always, let me know if you have any questions.