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September 7, 2011 Fantasy BeatThe Importance of Popups
Earlier this season, I penned a piece about the holy trinity of skills that I look for in pursuing starting pitching: high groundball rate, high strikeout rate, and solid strikeout to walk rate. The desire for those skills are rather obvious in that groundballs are the least likely of the batted ball types to become home runs, the less balls in play mean less chance of batted balls becoming hits, and command of the strike zone helps pitchers stay ahead in counts, which is statistically favorable. Even though that is my preferred model for a pitcher, I (nor anyone else that subscribes to that model of talent acquisition) can be closed-minded enough to shun pitchers that do not fit into that classification. After all, if you were to cross off every pitcher that did not have at least a 50 percent groundball rate this season, you would be excluding a likely Cy Young Award winner, a strong runner-up for that award, and two strong Rookie of the Year candidates (plus scores of other useful pitchers). One reason some pitchers without the optimum groundball rates can be tolerated is because they can invoke another handy weapon—the infield fly. This soft pop-up batted ball type is a pitcher’s next best friend behind the strikeout because of its extremely low success rate in resulting in a base hit. After all, unless every person on the infield collides at once, rendering each fielder unconscious, that batted ball type is not going to result in a home run, and only the Phil Mickelson type flop-shots off the bat have a chance of landing safely in play without being caught by a fielder. Thus, a pitcher with a heavy fly ball rate is more palatable if a good portion of those fly balls are not leaving the infield. If we consider 30 percent to be a “heavy” amount of flyballs, there are 47 starting pitchers in baseball whose fly ball rate is at least 30 percent this season. Their FIP’s have a wide range as well, from Cory Luebke’s 2.80 this season to Bronson Arroyo’s 5.43. However, if we sort that group by infield pop-up rate, the results become a bit less radical. Of those pitchers, 22 have an infield pop rate of at least ten percent this season, none have a FIP over 5.00, and 12 of those 22 pitchers have a FIP under 4.00 this season.
On that list, there are several pitchers whose skills fall outside the pre-defined Holy Trinity yet are finding some success with the help of the infield pop-up rates. Jeremy Hellickson has 12 wins, a 1.13 WHIP, and a 2.90 ERA despite a pedestrian strikeout and K/BB rate. While his .230 batting average on balls in play is a big help (and one of the reasons his FIP is considerably higher than his ERA), his 14 percent popup rate is the third highest in baseball. That high infield fly rate is one of the reasons why Hellickson’s BABIP is so low (along with a home ballpark that suppresses offense, great team defense, and a little luck). Hellickson’s .230 BABIP looks a bit better when you consider the fact that the highest BABIP on the Rays’ starting staff this season (minimum 100 innings pitched) is David Price at .281. If you eliminate James Shields’s awful BABIP last season, this will make two consecutive seasons in which every starter on the Rays’ staff has had a BABIP below .282. James McDonald is also getting help from his infield fly rate. He is 9-7 on the season with a 3.98 ERA despite a 1.3 home run rate and a 1.9 strikeout-to-walk rate. The fact that he has been able to turn ten percent of his fly balls into popups has helped keep his home run rate in check as his .296 BABIP is not as fortunate as Hellickson’s this season. After seasons of toiling around in multiple organizations, Bruce Chen has found some success with the Royals and has once again provided fantasy owners with double-digit wins despite a less than desirable skill set, and his ERA has been 4.11 this season despite an undesirable FIP. Let’s examine how pitchers with high and low popup rates fare as a group. Below are the FIPs and BABIPs of the two groups of pitchers:
Jered Weaver and Clayton Kershaw have had at least a 12 percent infield fly rate in each of the last four seasons. Both are shining examples that this is more of a skill than just random luck. But that begs the question, how do stronger infield fly rates affect FIP and BABIP? The table below shows the difference between groups, this time with 5 percent and 12 percent as the cut-off rates.
There is a slight gain in BABIP but the difference in FIP is negligible. As you start to review 2011 in preparing for your 2012 draft, do not automatically dismiss all low BABIPs as candidates for a regression to the mean. Be sure to look at a pitcher’s batted ball rates as those pitchers who display an ability to induce a popups at a high frequency should have less of a regression to deal with than a pitcher whose is unable to do so, relying instead upon luck to drive his BABIP.
Jason Collette is an author of Baseball Prospectus.
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Good stuff Jason.
Did you notice anything in your research suggesting that inducing pop-ups is a repeatable skill? If so, is there something inherent to these pitchers that suggests they can do this year after year?
Yes -- there was an article linked earlier in the story by Dave Studeman (http://www.hardballtimes.com/main/article/never-swat-an-infield-fly/) . I t points to work done by Mitchel Lichtman and later Michael Humphries on batted ball types and defensive regression analysis that "pitchers actually seem to have different levels of skill of inducing them (pop-ups)."
According to the work, flyball pitchers seem to be better at inducing infield pop-ups, which makes a lot of sense on the surface. Of the top 20 pop-up rates this season, just Lester and Halladay have groundball rates of 50% or more.
I showed above how both Weaver and Kershaw have consistently posted high pop-up rates making it a repeatable skill for them. Halladay has had double-digit rates six different times in his career but has also gone from 9% last season to 16% this season so his ability is bit different. Ted Lilly is at 14% for his career and has never been below 10% at any point point and he's an extreme fly ball pitcher.
I see two things that help - flyball pitching and deception. Weaver has that delivery that is incredibly tough to pick up and he works up in the zone. Kershaw has a similarly tough delivery but that hammer of his is tough to square up as well. Hellickson's comes from how clean his delivery is as he hides the ball and the fact his arm speed and delivery between his fastball and change-up are identical.