Finding Pitching Sleepers With Infield Fly Rate

My article today spawned after listening to The Sleeper and the Bust podcast when Paul Sporer interviewed NBFC’s Main Event champion Rob Silver. The entire podcast is a must listen, but one part sparked my interest. Rob mentioned he uses infield flyball rate plus strikeout rate minus walk rate to value pitchers (55:45 point). Silver successfully targeted Kevin Gausmann, Marco Estrada, and Rick Porcello late in his draft by using this stat combination. I will create the same filter to find 2017 sleepers.

There is no easier ball to catch than the infield fly. It’s an easy out. In those few instance when they errantly fall to the ground, a fantasy owner shouldn’t worry since the rest of the inning’s runs won’t count because of the error.

Besides being an easy out, a player’s infield fly rate stabilizes with just over a half season’s data. While infield flies don’t stabilize as fast as strikeouts, they do become stable within a season.

Infield fly rate (IFFB%), especially as we represent it here at Fangraphs, misleads the user. The IFFB% listed indicates the percentage of flyballs (FB%), not all batted balls, which are hit in the infield. To get the infield popup rate, the IFFB% must be multiplied by the FB%. The confusion doesn’t end yet.

A person shouldn’t combine strikeout rate (K%) and popup rate because they use separate denominators. Strikeout rate uses plate appearances and popup rate uses balls in play. To solve the conflict, I will use infield fly balls per plate appearance. The strikeouts and infield flies now have the same denominator and can be added together without enraging the Math Gods.

To finish Silver’s recommendation, walk rate (BB%) is subtracted to get a pitcher’s value. With the math out of the way, time to look at some results. First, no easy method exists on our stats pages for the data, so I made all the data since 2002 available.

To limit the dataset, here are the 2016 leaders (min 100 IP, 50% of games started) along with their NFBC average draft position (ADP).

Some thoughts on some players listed above.

• It’s no surprise to see Kershaw and Scherzer occupying the top two spots.
• Many of the surplus value pitchers (Darvish, Hill, Strasburg, Velasquez, etc.) have injury histories. The above equation represents just one aspect of a pitcher’s value, the other aspect is being able to throw deep into games all season long. League depth determines how to value injury prone pitchers. In shallow leagues, I’d target the injury risks knowing decent waiver wire options exist. In deep leagues, fewer options exist so health may override talent.
• Robbie Ray and Michael Pineda say, “Hi”. Recently, I found their inability to throw their breaker for strikes leads to getting hit hard. Even with their batted ball struggles, I would target them at their current values.
• It will be interesting to see how Drew Smyly’s ADP changes after being traded to the Mariners.
• The Cubs front line starters, Jake Arrieta, Jon Lester, and Kyle Kendrick all took major hits compared to thier ADP. The Cubs historically good defense limited hits and therefore runs allowed for this trio. The defense will be good again, but this trio’s owners should some regression.
• Rick Porcello looks to be undervalued … again. I don’t think his 2016 season was a fluke as he improved as the season progressed. His K-BB% went from 16% to 19% and his FIP dropped from 3.84 to 2.95. He’s still a value.
• Matt Andriese name seems out of place, but it shouldn’t. He doing his best Rich Hill imitation with a low groundball fastball (24%) and high groundball breakers (slider at 56%, change at 64%, and curve at 55%). His league average 42% groundball rate looks unimpressive but examining his pitches individually points to a unique skillset.