No one in baseball this season has thrown the slider more frequently than Padres reliever Luke Gregerson. At 60 percent of his total pitches, Gregerson edges out the Cubs Carlos Marmol, but after that there aren’t any pitchers who have thrown the slider even 50 percent of the time. They both employ the pitch for good reason. Though they have thrown far fewer pitches than noted slider hurlers Colby Lewis, Anibal Sanchez, and Francisco Liriano, they rank third and fourth in the league in wSL.
Just last week Matthew examined Marmol’s insane strikeout rate, two batters per inning pitched. He also walks a ton, 5.40 per nine, and when hitters make contact they have produced good results, a .369 BABIP. Yet only four of 28 baserunners have come around to score. That’s where his strikeout rate comes into play. Runners reaching base is no big deal with Marmol on the mound. A few more sliders and he can set down the next hitter. The strikeout rate, in fact, is likely a large part of his insane 91.2 percent strand rate.
Though his strikeout rate isn’t Marmolian, Gregerson’s 10.05 per nine puts him near the top of the league. Where he really stands out, though, is in his control. A pitcher who throws sliders so frequently is bound to walk hitters, but not Gregerson. He has walked just two in 28.2 innings, a rate not only far superior to Marmol’s, but good enough for second in the league. Only the Cardinals Ryan Franklin has walked hitters at a lesser clip, just one in 24.1 innings. Though perhaps Cliff Lee‘s four walks in 52.2 innings is a bit more impressive.
Looking back on R.J.’s article from last September, this isn’t exactly new for Gregerson. He was barely hittable then, and that has carried over into this season. Yet much has changed. He threw the slider 49.6 percent of the time last year, still a high mark, but not as frequent as this season’s 60 percent. The results have shown up in the batted ball data. Opponents have a .170 BABIP against him, and have managed a line drive rate of just 12.5 percent, both marks falling far below last year’s. While some of that might be luck, the slider plays a prominent role. It looks like hitters just can’t square up the slider, even if they know it’s coming.
When his slider isn’t working, Gregerson has little to work with. It appears that this has only happened twice this season. The first came in Gregerson’s first appearance of the season. Manager Bud Black said that Gregerson’s slider “didn’t look right” in that outing against the Diamondbacks, who allowed three hits and a walk in just a third of an inning. Then, in an appearance on May 14th, he hung a slider to Matt Kemp. That remains the only home run Gregerson has surrendered this year. It comes as little surprise that Gregerson struck out no hitters in those two appearances.
Whenever I see a pitcher who throws breaking pitches so frequently, I wonder about long-term health prospects. Can a pitcher possibly get by while twirling the ball more than every other pitch? Mike Wuertz, who threw sliders more frequently than any other pitcher last season, missed the first month of 2010 with shoulder tendinitis. Mitch Stetter, who threw over 60 percent sliders last year, hasn’t gotten hurt, but the Brewers optioned him to AAA after 3.2 horrible innings this year. Brad Lidge, who threw 56.2 percent sliders during his dominant 2008 season, spent time on the DL in 2009 and 2010. Bill Bray, who threw 50.9 percent sliders in 2008, underwent Tommy John surgery in 2009. Kiko Calero, league leader in slider percentage in 2007, missed 121 days between the end of 2008 and 2009 with various shoulder injuries.
There are some survivors, of course. There always are. Marmol himself hasn’t missed time with an arm injury since 2006, and that was before he started throwing the slider 50 percent of the time. Wuertz has thrown more than 60 percent sliders in each of the past three years and this year was the first time he spent time on the major league DL with arm trouble. There seems to be some correlation in the anecdotes and the data, which does cause some concern for Gregerson’s future.
The Padres’ bullpen has benefitted greatly from Gregerson and his slider. The unit claims the NL trifecta of fewest walks, most strikeouts, and lowest batting average against. They’re getting help from everywhere, but Gregerson has been a particular bright spot this season. The high slider frequency does cause a little concern, but for right now it’s his nearly unhittable weapon. I can’t imagine being an opposing hitter and standing in to face him.