A.J. Burnett’s Curve Not A-OK

New York Yankees right-hander A.J. Burnett was rolling along last night against the Minnesota Twins, whiffing five batters, walking two and trading zeros with Scott Baker through five innings. And then, for the first time in the short history of Target Field, the rains came and delayed the action. The game was eventually suspended and will be picked up today.

Burnett pounded the zone with his fastball, tossing 35 of his 50 heaters for strikes (70 percent). But while Mother Nature threw a nasty curveball last night, Burnett missed the mark with his hammer — just 10 of 23 curves garnered a strike (43 percent).

According to our Pitch Type Values going back to the 2002 season, Burnett’s deuce has been one of the best offerings in the game. Per 100 pitches thrown, the low-80’s breaking pitch has been worth +1.6 runs above average. Over the 2007-2009 seasons, Burnett’s curve had runs/100 values of +2.03, +1.23 and +1.47, respectively. And he went to the pitch often. Never known for his changeup, Burnett used his curve 26.3 percent in ’07, 29.2 percent in ’08 and 31.1 percent last season.

In 2010, however, A.J. can’t seem to find his plus curveball. The pitch has a -0.14 runs/100 value. According to Pitch F/X data from texasleaguers.com, Burnett’s curve has been thrown for a strike only 47.9 percent of the time this year, compared to 56.4 percent in 2009 (the MLB average is about 58 percent). Batters have whiffed at 12.1 percent of curveballs thrown in 2010, a significant decline from last season’s 16.7 percent whiff rate (11.6 percent MLB average).

Not getting results with the curve, Burnett appears to have lost confidence in the pitch. He has thrown his breaking ball 23.5 percent of the time, preferring to go to his 93-94 MPH fastball on nearly three-quarters of his pitches. Burnett has typically tossed his fastball about two-thirds of the time, but his 2010 heater usage has few peers — among starting pitchers logging at least 50 innings pitched, Burnett trails only Colorado’s Aaron Cook and Seattle’s Doug Fister in fastball percentage.

Burnett’s four-seamer and sinker have been decent, with a combined run value right around the big league average. But those pitches don’t induce nearly as many swings and misses as breaking stuff. Burnett’s four-seamer has been whiffed at 6.4 percent (6 percent MLB average) and the sinker has a 5.2 whiff percentage (5.4 percent MLB average).

As a result, A.J. isn’t getting K’s like he usually does. Burnett has 6.39 K/9, his lowest mark since 2000 with the Marlins and nearly two punch outs per nine frames lower than his career average (8.3 K/9). The 33-year-old’s swinging strike rate is just seven percent, compared to the 8.3 percent MLB average and Burnett’s 10.2 percent mark since 2002. A.J.’s 83.2 percent contact rate sits well above the 80-81 percent big league average and his 76.5 percent clip dating back to ’02. Since inking a five-year, $82.5 million deal with the Yankees prior to 2009, Burnett hasn’t fooled batters near as much.

His 2010 xFIP (4.35) is similar to his 2009 mark (4.29), as Burnett has walked fewer batters and induced more ground balls compared to last season. But he isn’t pitching like the high-octane starter we came to know in Florida and Toronto. For A.J. to start getting more K’s, he’s going to have to rediscover his curveball.