Generally speaking, pitchers like ground balls. They don't go for hits as often as line drives do, and they don't go for extra bases as often as fly balls do — they strike a comfortable balance between the two. Although many ground ball pitchers don't post the strikeout or walk numbers we'd like to see, the contact they generate allows them to pitch well. We in the sabermetrics crowd like these hurlers, because we see them as underrated assets.
Recently, though, some have pointed out a flaw with most ground ball pitchers, a facet of their performance that may make them overrated: The few fly balls they do sacrifice can inflict some serious damage. SIERA, one of the most accurate ERA estimators available, takes into account an interesting characteristic of fly ball pitchers, as Matt Swartz (its creator) noted:
SIERA assumes that pitchers who allow more fly balls have below-average HR/FB rates, and that’s exactly what happens.
The converse applies as well. In a study at The Hardball Times, Matthew Murphy analyzed several extreme ground ball pitchers and observed that they generally owned higher home runs-per-fly ball rates than their fly ball-inclined counterparts. The cause? Popups, which ground ballers don't tend to accumulate and help depress home runs (since most balls that remain in the infield won't leave the yard). Murphy concluded that because of this, the baseball community shouldn't hold ground ball pitchers in as high an esteem as it does.
Enter Kyle Gibson. The one-time top prospect debuted full-time for the Twins in 2014 and posted decent enough results — a 101 FIP- and 2.1 WAR in 179.1 innings will earn him another crack at the rotation this year. At 27, he doesn't exactly have youth on his side, but he can nevertheless bring some attention to a team that sorely needs it.
So how did Gibson do what he did? Well, he didn't punch out many batters with a subpar 14.1% strikeout rate. He also issued free passes at a 7.5% clip, around the average mark for starters. Rather, Gibson derived his prosperity from long balls, or the lack thereof: His 0.60 HR/9 ranked a cool 13th in the majors. And that's where it gets interesting.
As the loquacious introduction might have indicated, Gibson is a ground ball pitcher. 54.4% of the balls hit against him in 2014 didn't go airborne, the seventh-highest rate in baseball. Based on what we've seen earlier, we might then look at his 7.5% HR/FB and deem it a fluke, destined to regress. But his story doesn't end there.
Many pitchers keep the ball on the ground; many pitchers keep the ball in the infield when the batters put it in the air. Most pitchers don't fall into both groups. Kyle Gibson is not most pitchers. Hence, his 13.6% IFFB%, placing fourth in the world. Together with his aforementioned place in the ground ball hierarchy, this sets him apart — only two other qualified pitchers in the batted-ball era (since 2002) have finished in the 90th percentile in both ground balls and infield fly balls:
Any time you have something in common with Doc Halladay, you've done something right. (And hey, Padilla had some solid years too.)
Now, what's happened in the past won't necessarily occur again in the future. While we can pretty confidently say that Gibson will remain a ground ball pitcher, we don't know that the popups will remain. Matt Klaasen's work with correlations has illustrated that the latter statistic fluctuates a lot, with a measly .422 year-to-year correlation. Perhaps this will disappear in the coming season, and Gibson will allow home runs at a more pedestrian level.
Then again, Gibson has some basis for this, skill-wise. His four-seam fastball, which he threw 19.5% of the time in 2014, induced a popup in an incomparable* 15.8% of all balls in play. From his zone profile, it becomes clear why that happened:
*I mean that literally. Dangit, BPro, why don't you have popups on your PITCHf/x leaderboards?
Gibson utilized his four-seamer entirely differently than he did any other pitch, and he uncoincidentally saw entirely different results from it. Sure, it didn't get him too many ground balls — 40.5% worm burners, only marginally better than average — but the weak contact he generated from avoiding the zone compensated for that. If he continues to execute in this manner, the infield fly balls shouldn't disappear.
Rarities in baseball don't come along often (otherwise, we couldn't really call them rare). One such creature is the hurler that nets easy grounders and easier flies, a deadly combination. For most pitchers, that recipe simply won't work, but Gibson has found a way to do so. Maintaining this ability might propel him into the ranks of the elite and could do the same for his long-suffering club.
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Ryan Romano is an editor for Beyond the Box Score. He also writes about the Orioles on Camden Depot and on Camden Chat that one time. Follow him on Twitter at @triple_r_ if you enjoy angry tweets about Maryland sports.