In a general sense, A.J. Burnett performed well in his debut season for the Yankees. Sure, he tossed a few clunkers, but he also had his share of dominating performances. At the end of the season that averaged out to a 4.04 ERA, right around his 2008 ERA of 4.07. That he pitched over 200 innings for the second straight season, the first time he’s accomplished the feat in his career, was a further positive. In a number of ways, however, Burnett’s season represented a step backward.
In 2007, after an injury-shortened debut season with Toronto, Burnett accomplished something he never did in the National League: he struck out more than a batter an inning. He did it again in 2008, and that probably played a role in the Yankees’ decision to sign him. It was an odd trend, of course, as pitchers tend to rack up more strikeouts in the NL, where pitchers hit instead of the DH. During these two years Burnett also kept his walks in check, around 3.50 per nine. Yet in his 2009 campaign Burnett declined in both areas.
His strikeouts remained high, 8.48 per nine innings, right around his career National League performance, but not quite at the level of his previous AL East experience. His walks also shot up, 4.22 per nine, his highest rate since 2001 (discounting his 23 innings in 2003). But again, despite declining about 10 percent in strikeout rate and increasing about 27 percent in walk rate, Burnett produced similar results as 2008. My question is whether this is a good sign, or whether it represents a boatload of good luck.
Looking a bit deeper into Burnett’s performances makes me think that luck played a big factor in his 2009 numbers. The first set of data that stands out is his ground ball to fly ball ratio, 1.09, the lowest of his career, and by a decent margin since 2003. His ground ball rate has declined over the past three years, going from 54.8 percent in 2007 to 48.5 percent in 2008, and finally to 42.8 percent in 2009. In that time, his fly ball rate has increased from 29.8 percent to 32 percent to 39.2 percent. This led to an xFIP of 4.29 and a FIP of 4.33, both a bit above Burnett’s actual ERA. His defense, it would seem, helped him out a bit.
We know that Burnett lives on his curveball, a nasty pitch that acts somewhat like a slider, diving down and away from right-handed batters, though the down and inward motion seems to foil lefties as well. He lives on swings and misses out of the zone in that regard. Yet in 2009 hitters made more contact in pitches outside the zone, 51.1 percent, than in any other year of his career. Burnett’s contact rate as a whole jumped last season, while his number of pitches thrown inside the zone was the lowest of his career (again, discounting 2003). What’s worse, hitters swung at fewer pitches outside the zone, 22.1 percent, than they had since he moved to the AL in 2006. His overall swing rate was, again, the lowest of his career.
The curveball, however, seems to be fine. According to FanGraphs’s pitch type values, his curve was as good as ever, perhaps among the best it has been in his career. It was worth 15.4 runs above average, higher than in any of the Blue Jay years, and higher than any year of his career except 2005. What hurt him, it appears, was his fastball, which ranked -13.0, the lowest of his career and, on a per 100 pitch basis, the 22nd worst fastball in the majors among pitchers who threw more than 150 innings.
Does the fastball decline explain Burnett’s increased walks, decreased strikeouts, and decreased ground balls? I think it has to, at least in some way. Again, look at Burnett’s last three seasons, and you’ll see increasing fly balls and decreasing ground balls. You’ll also see a decrease in his fastball value, from 8.2 runs above average in 2007 to 5.9 runs below average in 2008 to 13 runs below average in 2009. While we can’t determine specific causation, there seems to be something of a correlation there.
What’s most troubling about A.J.’s trending numbers is that we should have expected an uptick in performance over Toronto. He pitched in the AL East for three years and had to face the powerhouse Yankees offense during that time. By moving to the Yankees, he moved from that to having to face the Blue Jays lineup. So it appears that his workload got a bit easier. Yet his peripherals declined. I don’t like the looks of that.
Perhaps Burnett went through a period of adjustment to the rigors of pitching for the Yankees, and will recover his previous form in 2010. We know he has the stuff to do so. We saw A.J. at his best in 2009, one-hitting both the Mets and the Red Sox. We also saw him at his worst, giving up eight and nine runs to the Red Sox, seven to the White Sox. Hence Good A.J. and Bad A.J. These numbers don’t show whether we’ll see more of Good A.J. in 2010, though they do show why it appeared Bad A.J. showed up more than he really did.
Credit: AP Photo/Elise Amendola