How A.J. Burnett Got His Groove Back
A.J. Burnett finished off a successful West coast road trip for the Phillies with eight shutout innings against the Diamondbacks on Sunday afternoon. The win, completed by Jonathan Papelbon, left the Phillies with a 6-4 record over their ten games against the Rockies, Dodgers, and D-Backs. For Burnett, it was his third successful start out of three since being diagnosed with — and choosing to play through — an inguinal hernia.
The hernia isn’t affecting him too much. If anything, it’s made him better. Here’s a look at those three starts:
- April 17 vs. Braves: 7 IP, 0 ER, 3 H, 2 BB, 5 K (no-decision win)
- April 22 at Dodgers: 6 2/3 IP, 2 ER, 6 H, 1 BB, 5 K (no-decision win)
- April 27 at Diamondbacks: 8 IP, 0 ER, 5 H, 0 BB, 8 K (win)
- Total: 21 2/3 IP, 2 ER (0.83 ERA), 14 H, 3 BB, 18 K
So, what changed — besides the injury? It wasn’t a better fastball. His average fastball velocity on Sunday was the same as it was on April 11 against the Marlins, the game in which he couldn’t go five innings and after which would be diagnosed with the hernia.
There are a few factors. One is that he almost entirely scrapped his change-up, according to Brooks Baseball.
In that start against the Marlins, Burnett couldn’t get anything on it. The change-up was about 4 MPH lower than it was in his two previous starts as well as the three starts that ensued.
Here’s a similar chart showing the maximum speed each pitch got up to:
As a result of ditching the change-up, Burnett used his sinker more often. Without having asked him, it’s tough to know exactly why the change occurred and if it had anything to do with his injury.
The change might have also had something to do with the handedness of opposing hitters. In his first three starts, 57 percent of hitters were left-handed and 43 percent were right handed. In his most recent three starts, those percentages were 28 percent and 72 percent, respectively. It makes sense — change-ups are more effective against opposite-handed hitters. Cole Hamels, for instance, threw 709 of his 854 change-ups (83%) to right-handed hitters in 2013. It’s not always the case [that a pitcher throws most of his change-ups to opposite-handed hitters], but it is more often than not the case.
With the increased use of the sinker, of course, Burnett induced more ground balls. His ground ball rate in his first three starts was a respectable 51 percent, but increased to 58 percent in his most recent three starts. Given that his line drive rate stayed nearly the same, these ground balls came at the expense of fly balls. Whether it’s weaker handedness, the platoon advantage, or more efficient defense, those ground balls have become outs much more often as well. He allowed a .314 batting average on balls in play (BABIP) on ground balls before; .241 after.
There’s been one more very noticeable change, pertaining to the location of his pitches.
|vs. RH hitters||Inside||Middle||Away|
|First 3 starts||29.7%||23.4%||46.9%|
|Last 3 starts||16.1%||22.4%||61.4%|
Burnett has stayed away from right-handed hitters more often recently.
|vs. LH hitters||Inside||Middle||Away|
|First 3 Starts||48.4%||20.6%||31.0%|
|Last 3 Starts||56.5%||21.2%||22.4%|
Burnett has gone inside on left-handed hitters more often recently.
As a result, right-handers’ collective weighted on-base average (wOBA) has gone from .300 to .191, and lefties’ wOBA has gone from .446 to .281.
Whether it was the injury itself, the frequency in which he had the platoon advantage, or just a strategic shift, Burnett has been significantly more effective since April 17. Burnett says he will try to pitch through the hernia as long as there isn’t too much discomfort. If he can continue to be anything like the pitcher we have seen over the last two weeks, the Phillies’ rotation will be quite menacing.