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%).

Adam Wainwright's Wicked Curve

Adam Wainwright has both tested his reconstructed elbow and tortured hitters with his curveball this postseason. Wainwright, who stretched the Cardinals' NLCS lead over the Giants to 3-1 last night, has struck out 20 hitters overall. Seventeen of those whiffs have been on curveballs. Simply put, Wainwright has left a curveball high in the strike zone about as often as TBS has run a Bruce Springsteen-less commercial break.

The 31-year-old righty has unleashed 75 curveballs this postseason. Just four of those curves, or about five percent, were located in the upper third of the strike zone. For comparison's sake, starting pitchers threw 18% of their curves high in the zone during the regular season, and they have done so about 14% during the playoffs.

Against righties, Wainwright is placing his curve low and away:

Wainwright's curveball location vs. righties

He's mixing it up more against lefties, throwing low-and-away curves for strikes but also burying pitches in the dirt:

Wainwright's curveball location vs. lefties

Those earth-bound breaking balls have produced most of Wainwright's strikeouts:

Location of Wainwright's strikeouts with his curveball

Hitters have gone just 2-for-26 against Wainwright's hammer this postseason. If the Cardinals do finish off the Giants, Wainwright's curve could be in for a challenge against the Tigers. Detroit has a collective .427 slugging percentage against curveballs thrown by righty pitchers this season, far above the .335 major league average. Just don't expect Wainwright to hang one, Miggy and Prince.

Top Curveballs by Contact

(Min. 50 curveballs thrown in 2011)

Prior to the beginning of this season, we took a look at the change in Zack Greinke's (MIL) curveball between 2009 and 2010.  Getting his curveball back on track is important for Greinke this year, especially if he is going to get back to his Cy Young form from two years ago.

So far this season, batters are swinging and missing at his curve at a higher rate than against any other pitchers' curve.  He's yielded only one hit off the pitch, a ground ball single to Jose Tabata (PIT) on May 15th.

In 2009, Greinke had an average BrkZ (vertical inches of break from spin) reading on his curveball of -4.2.  In 2010, that number was cut in half to -2.0 inches of downward break - and as noted in the previous post on Greinke, batters were teeing off on it.  This season, his curve has a BrkZ reading of -6.8.  While his overall numbers haven't been great through his first 4 starts, a working curveball is a good sign for the 2009 Cy Young winner.