FanGraphs: What's Lackey lacking?

John Lackey has never been a strikeout artist. He’s never struck out 200 in a season nor reached the hallowed ground of recording one K per inning for a season. But this year, it’s getting a little ridiculous. He’s striking out batters at a career-low rate (5.58 per nine innings) and he’s getting battered around the park, such as he did in a 5-1 loss to the Detroit Tigers on Sunday. This isn’t what the Red Sox thought they were buying with their $85 million.

Normally, when a pitcher has an unexpected bad start, the traditional "luck" statistics (batting average on balls in play, strand rate and home run rate) tell the tale. But in this case, they don't. Lackey has a .308 batting average on balls in play (which usually ends up at .300 across baseball) and has stranded exactly 70 percent of runners, which is also right around league average. He’s even giving up the standard amount of home runs per fly ball (8.5 percent this year, usually around 10 percent across baseball). It’s not a case of poor luck, it seems.

Looking at batters' swing rates when they step in the box against Lackey doesn't help much, either. Batters are reaching at offerings outside the zone about as often as usual. It seems that Lackey is missing the zone a little (45.2 percent in the strike zone, 50.4 percent career) and batters are making more contact than usual (84.1 percent contact rate, 80.3 percent career). But why are batters making more contact with his pitches?

He hasn’t lost any velocity. His fastball and curveball are within 0.2 mph of their career levels. The slider and changeup have actually gained oomph, but perhaps that is part of the problem. The difference between his fastball and changeup has gone from 8.2 mph for his career to 7.1 mph this season. But Lackey throws the changeup only around 5 percent of the time, so that effect probably isn’t huge.

The answer may lie in Lackey’s curve in the end. At FanGraphs, we keep a statistic that tries to put value on the results of each type of pitch in a pitcher’s arsenal. By using game state statistics before and after a slider, for example, we can assign value to that pitch. Looking at Lackey’s career, his fastball (plus-27.6 runs career) and curve (plus-51.8 runs career) have always been his best pitches. His slider has usually been around scratch or better (plus-6.4 runs career).

This year? His fastball (plus-1.1 runs) and slider (plus-1.2 runs) have been doing fine. For only the second time in his career, however, the curveball is currently negative (minus-1.6 runs). Though neither the horizontal movement, vertical movement nor the velocity numbers show anything really unique about his curveball this season, the pitch is just not providing good results for Lackey this year. Why? It's hard to know, but don't be surprised if we start to hear murmurs about him tipping his pitches.

On Sunday, Lackey threw the curve 31 times. It actually resulted in a strikeout three times, so it wasn’t terrible, but the curve also resulted in three singles and Ramon Santiago's two-run homer. If you’re wondering what Lackey is lacking, it seems it’s his signature curve.

Eno Sarris is a writer for FanGraphs.