"I'm just not getting swings on pitches I'm used to getting swings on," he said. "The balls they're hitting are just getting too much of the plate, I guess."
Burnett's problems for much of the season have originated from his inability to command his curveball. His bread-and-butter pitch last year, Burnett's curveball has been inconsistent throughout 2010. He has thrown it for strikes less frequently and not generated as many swings and misses on the pitch as in the past.
According to the pitching analysis of Texas Leaguers (using statistics from MLB.com's Gamdeday), Burnett has thrown his curveball for a strike 52.8% of the time this season, down from 56.3% last year. And hitters are making better contact against hit, swinging and missing on the hook 13.2 percent of the time this year, a decrease from the 16.8 percent a season ago. As a result, Fangraphs lists Burnett's pitch-type value with his curveball at 4.50 runs below average in 2010. For comparison, last year it was 16.0 runs above average, good for fourth in the Majors.
Burnett's troubles commanding his curveball mean he's falling behind more hitters, who can then spend more time sitting on his fastball. As a result, he's allowing a career-high 9.9 hits per nine innings while posting his lowest strikeout rate per nine innings since 2001.
"I was just behind a lot," Burnett said of his outing on Friday. "Some of the curveballs, they're good 0-2 curveballs, but what good does that do you 0-0?"
Manager Joe Girardi thinks Burnett's issues may be mechanical.
"Most of the times a pitcher's issues start mechanically. Something gets off a little bit, and it's harder to throw the ball where you want to," he said. "[With Burnett's curveball], that's somewhat of a mechanical thing where the arm slot gets a little bit too low. When it does that, it's not going to have that same bite down. Sometimes it may go across more or you'll leave it inside."
Girardi, though, still think there's time for Burnett to turn it around and regain the form that helped him pitch the Yankees to a World Series last autumn.
"He's done it before in his career where he's had struggles and he's come back and had long periods of time where he's been on track," Girardi said. "Sometimes it seems harder than others. It's basically the same principles."