A.J. Burnett's Curveball Racking up Ks

A.J. Burnett takes the mound tonight against Washington boasting the top strikeout rate (12.3 per nine innings pitched) among National League starters. His hook is the reason why. Burnett's sinister knuckle-curveball has already felled 29 batters this season, which is the highest total for any breaking or off-speed pitch in the majors aside from Yu Darvish's slider. Here are three reasons why Burnett's curveball is so effective, in honor of the many punch outs that the pitch has produced.

• A.J. almost never hangs his curveball high in the strike zone. He has thrown just four percent of his breakers in the upper-third of the zone this season. That's lowest among all starters who have tossed at least 100 curves in 2013.
• He's not just keeping the ball down -- he's also avoiding the heart of the plate. Burnett has placed 19% of his curveballs over the horizontal middle of the strike zone, well below the 24% average for MLB starters.

Burnett's curveball location in 2013

• Batters have swung and missed 47% of the time against Burnett's curve, tops among starters. The MLB average is a comparatively puny 27%. Almost all of Burnett's strikeouts with his curveball have been of the swinging variety (27 of 29, or 93%).

A.J. Burnett on the Block

With a starting rotation bursting with options and a possible need for a righty-masher to pair with Andruw Jones at the DH slot, the New York Yankees are shopping reviled right-hander A.J. Burnett. The 35-year-old has two years and $33 million remaining on the free agent deal he signed prior to the 2009 season, so the Bombers will have to swallow lots of Steinbrenner Bucks and take back little talent in return to find a suitor. Does Burnett have anything left? That depends upon whether you think he can halt his homer-prone ways outside of Yankee Stadium.

After a decent first season in New York, Burnett has suffered a huge split between his ERA (awful) and his peripheral stats (adequate). With a 5.20 ERA over the 2010-11 seasons, Burnett ranks ahead of only fellow free agent villain John Lackey (5.26) among pitchers making at least 60 starts. But judging by expected Fielding Independent Pitching (xFIP), which does a better job of predicting future ERA, Burnett's 4.17 mark is actually slightly below the 4.24 average ERA for American League starters in 2010-11.

Burnett is striking out plenty of hitters, though he's also walking more than his fair share. But the biggest problem is that hitters are taking him deep when they hit a fly ball against him:

Player	Strikeout Pct.	Walk Pct.	HR/FB Pct.
Burnett 2010-11	18.9	9.8	14.1
Avg. AL Starter, 2010-11	17.2	7.6	9.8

That huge home run per fly ball rate -- highest among qualified AL starters over the past two years -- has led to 1.3 big flys per nine innings pitched. Bronson Arroyo and Ted Lilly are the only pitchers with 60+ starts since 2010 to get whiplash more frequently.

Burnett's fastball and sinker are the culprits. Forty-seven of the 56 homers he has surrendered over the past two years have come against the heat. And the vast majority of those shots have come on fastballs/sinkers that are thrown belt-high and over the fat part of the plate:

Location of Burnett's HR surrendered, 2010-11

Is Burnett more prone to throwing fat pitches over the plate? Possibly. Since 2010, 25.1% of Burnett's fastballs and sinkers have been tossed to the horizontal middle of the strike zone. The average for AL starters is 24.5%. Burnett has thrown 3,884 fastballs/sinkers, so that's an extra 23 meatballs for hitters compared to the league average.

Those optimistic about Burnett turning it around can point out that home run per fly ball rate fluctuates much more than strikeout and walk rate, so he's more likely to give up homers around 11% of the time a fly ball is hit next year (his career rate) than 14% of the time. And Burnett's fly balls aren't traveling farther than they used to: batters hit fly balls an average of 281 feet against Burnett in 2010-11, compared to 282 feet during his more successful 2008-2009 seasons.

In a less hostile pitching environment -- say, Pittsburgh's PNC Park -- Burnett could re-establish himself as a league-average starter and produce something in the range of three Wins Above Replacement over the next two years. That sort of pitching is typically worth around $15 million on the free agent market, but those wins are less valuable to a rebuilding club and Burnett has barely been above replacement-level if you judge by ERA. Unless a team is really banking on a Burnett rebound, the Yankees might have to eat 20+ million to make a trade happen.

Yankees' Season May Ride on Burnett's Fastball

Facing elimination in Detroit tonight, Yankees manager Joe Girardi reluctantly hands the ball to A.J. Burnett. The much-maligned Burnett wasn't supposed to make a start in this series, but a Game One rainstorm that eliminated an off-day after Game Two foiled those plans. Now, the fate of the Yankees' season may rest on whether the right-hander can avoid getting taken deep on his fastball.

During the regular season, Burnett had a huge discrepancy between his ERA (5.15) and his xFIP (3.86), which estimates a pitcher's ERA based on strikeouts, walks and a regressed home run per fly ball rate. He struck out plenty of hitters (8.2 per nine innings pitched) and showed so-so control (3.9 BB/9), but he coughed up 1.5 homers per nine innings pitched. There's some degree of bad luck involved when a guy surrenders a big fly 17 percent of the time that batters hit a fly ball -- Burnett's career HR/FB% is 11.3 -- but badly-placed fastballs are big concern.

Opponents have swatted 23 home runs on Burnett fastballs this season, and have a .593 slugging percentage against the pitch that is 161 points above the league average. Among starters, only Ross Ohlendorf, Armando Galarraga, Brian Matusz, Kyle Davies, Edinson Volquez, Esmil Rogers and Barry Zito saw their fastballs get scorched more often. Many of Burnett's fastballs have been thrown at or above the belt:

Location of Burnett's fastball, 2011

Nearly 70 percent of Burnett's fastballs have been thrown to the middle or high portion of the zone (distributed about equally), and 21 of his fastball home runs given up have come in those locations. Belt-high fastballs are a no-no for most every pitcher, but Burnett isn't fooling hitters when he challenges them up in the zone. His miss rate with high fastballs is just 12 percent, compared to the 21 percent league average. Unless Burnett pounds hitters are the knees, he gets hammered:

Opponent slugging percentage vs. Burnett's fastball by pitch location

High: .617 (.380 league average)

Middle: .670 (.472 league average)

Low: .380 (.407 league average)

Odds are, Burnett (and his fastball) isn't as bad as his ERA suggests. But don't expect Girardi to stick with him in a jam tonight. Girardi told reporters, "I could have a very short leash (on him)." Given New York's strong back of the bullpen and Burnett's propensity to tire -- his OPS the first time through the order is two percent better than the league average, but it's 20 percent worse the second time and 42 percent worse the third time through -- it's the right call. Before then, Girardi and the Yankees will have to hope that Burnett can keep the ball down in spacious Comerica Park.