What Happened to Elvis Andrus's Power?

Elvis Andrus followed up his rookie season of 2009 with an almost identical batting average and a 13 point improvement in his OBP.  His power fell off a cliff however, from a low .373 slugging percentage to a poor .301. He went from 31 extra-base hits in 2009, including six home runs, to 18 with no home runs in 2010.  His results on fly balls may hold the key to why this happened.

The following graphs show pitch frequency location, movement, and batted ball results on fly balls in 2009:

Elvis Andrus fly balls 2009Note that Andrus hit balls low in the middle of the zone, but balls that dropped less than usual.  He could upper cut these pitches.  Note also the number of balls he pulled down the leftfield line.

Here's the same chart for 2010:

Elvis Andrus fly balls 2010The movement difference is subtle, but the balls are staying up and moving away from Elvis a bit more.  He's also chasing pitches higher in the strike zone, balls tougher to upper cut.  More balls moving away from him, where he's just getting under the pitch results in more flyouts the other way.  He didn't pull anything deep in 2010.

Death of a Bad Ball Hitter

Garret Anderson's career likely came to a close in 2010 when the Dodgers designated  him for assignment.  His last good season came in 2008.  He hit the ball wherever it was pitched:

Garret Anderson in play average in 2008

Garret could hit balls right down the middle, but his hot zones extended well out of the strike zone in all directions.  In 2009, he lost the middle and could only handle pitches in side or high. 

Garret Anderson in play average in 2009

His batting average dropped from .293 to .268.  In 2010 things got worse.

Garret Anderson in play average in 2010Garret totally lost the inside and middle of the plate.  He had to dive well out of the zone to get hits, and his batting average dropped to .181.  The classic bad ball hitter lost his ability to hit pitches in the strike zone, and ended a long career.

A.J. Burnett's 2010 Fastball

A.J. Burnett Overall

	AVG	OBP	SLG	wOBA
2009	.250	.338	.401	.334
2010	.285	.363	.457	.367

A.J. Burnett vs. LHB

	AVG	OBP	SLG	wOBA
2009	.222	.312	.352	.303
2010	.286	.373	.444	.368

A.J. Burnett had a much tougher time against left handed batters in 2010 than in his first season as a Yankee. In addition to the jump in his overall line, Burnett's K-Rate against LHB dropped from 24.9% in 2009 to 16.2% in 2010, striking out 43 fewer.

One thing that stood out was the drop in effectiveness in A.J.'s fastball in 2010, particularly against lefties.

A.J. Burnett's Fastball vs. LHB

	PA	AVG	SLG	wOBA
2009	274	.276	.474	.378
2010	190	.371	.648	.472

A.J.'s 2010 fastball averaged 93.2 MPH, a loss of 1 MPH from 2009. He was also much less effective in throwing the pitch down and away to LHB in 2010.

A.J. Burnett's Fastball vs. LHB 2009
A.J. Burnett's Fastball vs. LHB 2010
A.J. Burnett's Fastball vs. LHB (Highlighted Zone)

	PA	AVG	SLG	wOBA
2009	83	.250	.325	.271
2010	52	.298	.489	.378

In addition to the drop in velocity, Burnett's fastball also lost some downward movement. In 2010, his fastball was dropping at a rate of 11.6 ft/sec as it crossed the plate, about 4% less than 2009. This loss of movement combined with a drop in velocity may have contributed to his reduced K-Rate to lefties, and decreased the effectiveness of his fastball down in the zone.