Friday, August 29, 2008

What's Wrong: AJ Burnett

After getting a good response from the first installment of the What's Wrong Series, I've decided to continue on to a pitcher who may become very popular this off-season: AJ Burnett. The current Blue Jays pitcher has an opt-out clause in his contract which rumors suggest he will exercise following the 2008 season. The 31 year old right-hander is not having the best of possible contract seasons; unless you are judging by that antiquated, context-dependent stat known as "wins."

The difference between Burnett and my last subject, Justin Verlander, is age. A.J. Burnett is past his prime years, but is likely to get paid this off-season by a team looking for a cheaper alternative to Ben Sheets and C.C. Sabathia. But the buyer may beware that this season, although Burnett has put up some pretty win and strikeout numbers, there are a number of reasons for caution. Despite playing in a neutral park with one of the league's best defenses, Burnett sports a high ERA due in part to his tendency to give up line drives.

Forgetting about wins, Burnett has pitched poorly, compared to previous seasons. First, the traditional stats:

2006: 135.7 IP, 3.98 ERA, 1.30 WHIP, 7.83 K/9, 2.59 BB/9-- 115 ERA+
2007: 165.2 IP, 3.75 ERA, 1.19 WHIP, 9.56 K/9, 3.58 BB/9-- 119 ERA+
2008: 146.0 IP, 4.50 ERA, 1.41 WHIP, 9.32 K/9, 3.68 BB/9-- 93 ERA+

Indeed, Burnett's ERA, walk rate, and hit rate are at their highest levels since Burnett's 2000 season in Florida. While his strikeout rate in 2008 will be the second highest of his career (behind last season), it doesn't seem to have helped Burnett keep runs off of the board. To see why, we need to look at some of the batted ball data, courtesy of First of all, Batting Average on Balls in Play, a number which should be around .280 for the average pitcher. It's high this season for Burnett, at .318; pitchers with a high BABIP should see a correction in the following season. Following this, fewer hits should result in fewer runs for Burnett.

But, we can see by looking at Burnett's last six seasons that he his allowing fly balls (26.7% and line drives (18.7%) at a higher rate than any time in his career. Unlike Justin Verlander, Burnett is allowing a lot of batted balls on those trajectories which typically result in a higher slugging percentage. This season, hitters have a slugging percentage of 1.041 on line drives; that is, they average more than a single when they make line drive contact. In addition, a line drive off of Burnett becomes a base hit an incredible 79.4% of the time. Both of these figures are the highest since he's joined the Blue Jays.

Another useful way of looking at Burnett's results is to break it down by pitch outcomes. The folks at do this as well, and we can see what percentage of Burnett's pitches have been balls, called strikes, swinging strikes, fouls, or hit in play. Interestingly, Burnett gets the same rate of called and swinging strikes as last season, he also throws balls at a similar rate. The foul ball percentage is down a bit this season; he's about average for his career on the rate at which balls are hit in play.

It may be tempting to look at a pitcher with a high BABIP and high Line Drive percentages and simply say that he is less effective than last year. But there is another important component, obvious to folks who realize how context-dependent ERA is: the defense. While the trajectory of a batted ball may be influcenced by what kinds of pitches and locations thrown by the pitcher, ultimately the responsibility for making an out lies with the defense. The simplest measure of defense is to take the total number outs recorded by the defense and to divide by the number of balls hit in play. Baseball Prospectus tracks this, and the Toronto Blue Jays actually do quite well, recording outs on 71.1% of balls in play. This puts them fifth in the majors, trailing the most efficent Tampa Bay (71.7%) and lapping league-worst Cincinnati (67.9%). Last season, the Blue Jays had the best defensive efficiency in the league.

Despite the team numbers, something is going on with the defense behind Burnett. A standard way to neutralize the effect of defense on a pitcher's results is to only consider the Three True Outcomes- the homer, the strikeout, and the walk. By these defenseless measures we can see if a pitcher has a bunch of Derek Jeters playing behind him. The Hardball Times has a good tracker of this, called Fielding Independent Pitching (FIP). Burnett's numbers the last five years:

2004: 3.09
2005: 3.05
2006: 3.84
2007: 4.44
2008: 3.78

When a player's FIP is lower than his ERA, it suggests that the team is playing less efficient defense behind him. And the Blue Jays somehow have a Defensive Efficiency of just .679 when Burnett is pitching, versus that .711 overall. For comparison, Roy Halladay's got the Blue Jays defense working overtime, as they gobble up 71.8% of batted balls with the Doc on the mound. Once again, the culprit points back towards the hit trajectory-- a good defense doesn't suddenly get poor for Burnett, the problem is the type of batted ball the defense is facing.

In addition to his line drive problem, Burnett may be facing a new problem: left-handed batters. Throughout his career, Burnett has been able to get out both handed batters at an even rate: a .670 OPS against righties, a slightly higher .699 OPS against lefties. This season, though, lefties have raked him hard, to the tune of a .788 OPS that is his highest since his rookie season. Those left-handers make up a lot of Burnett's high BABIP as well, hitting at a .340 clip on balls in play. In addition to giving up more home runs to lefties than righties, he also walks them more often. One thing he's changed, according to the pitch f/x data, is throwing changeups to lefties:

Change-Up Rate
2007: Total: 9.86%, RH: 4.56%, LH: 14.78%
2008: Total: 6.16%, RH: 4.23%, LH: 7.83%

One difference between the seasons is that this year, splitters and sinkers are distinguished by Josh Kalk's system Last year, some of those pitches may have counted as change ups, but the majority of them were counted as fastballs. Still, the rate at which he throws off-speed pitches to lefties has dropped, and he's throwing curves slightly less often to left handers as well. This may not be to his benefit, as a great majority of Burnett's extra base hits come on his fastball, relative to his other pitches.

So what can we expect from a pitcher like A.J. Burnett?, with their similar pitcher tool, doesn't know what to think of Burnett. His career hasn't matched any pitcher for more than one season at a time, and currently is best matched with Chuck Dobson, who was completely out of baseball after his age 31 season, in 1975. Last year's top comparison is more interesting- Erik Hanson, who also followed a good age-30 campaign (ERA+ 115 in 1995) with a sub-par age-31 year (ERA+ of 92 in 1996). He then tore his labrum and was out of baseball two years later. The career-ending injury is always a possibility for the fragile Burnett, whose multiple arm surgeries are likely to catch up with him.

If he stays healthy, Burnett's new pitching coach may be looking for a better selection of pitches, especially to left-handed hitters. If he can curb his line-drive problem and go back to getting a higher percentage of ground balls, he could become a good pitcher for a few years. Personally, I hope the Yankees stay far away...

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