On May 20, 2011, Neil Walker was hitting .288/.361/.466 and was in the midst of an encouraging sequel to his strong rookie season of 2010. He had hit six home runs in his first 183 plate appearances of the year, putting him on pace to hit close to 20 bombs over the course of a full season. However, suddenly the home runs dried up, and he finished 2011 with only 12 long balls in 662 trips to the plate. That power outage has continued this season, as Walker has only hit two homers in his first 185 plate appearances.
Coming up through the minors, Walker’s biggest strength was always his ability to produce extra-base hits. Even when he struggled at Triple-A in 2008 and 2009, he still managed to hit for well above average power. The chart below shows his Isolated Power (which is simply slugging percentage minus batting average) over the course of his career. Take this data with a grain of salt, simply because it covers a multitude of levels while Walker was at various points of his developmental path. But it is pretty clear that he began hitting with good power once he got past his teenage years, until suddenly dropping off in the middle of the 2011 season.
Since May 21, 2011, Walker has posted a well below average Isolated Power (ISO) of .107 in 660 plate appearances. ISO generally stabilizes around 550 plate appearances, so we are looking at a very meaningful sample size at this point. But what has caused this power outage? Let’s first try to isolate the problem by differentiating between the kinds of extra-base hits. We can break that down into two categories: doubles/triples and home runs. Essentially, we are distinguishing between gap shots and balls hit over the fence. So, what has changed for Walker since May 20, 2011?
|Walker (9/1/2009 – 5/20/2011)||6.36%||2.60%|
|Walker (5/21/2011 – Present)||5.45%||1.21%|
|2011 League Average||5.02%||2.46%|
Based on these numbers, it looks like Walker’s largest concern is the loss of long balls. His rate of hitting doubles and triples has dropped slightly, but still remains above average. On the other hand, his home run frequency has fallen from above average to well below. The cause of this has been two-fold. Walker has hit far more ground balls in the past calendar year, sacrificing fly balls in the process.
|Balls in Play||GB%||FB%||LD%||IFFB%|
|9/1/2009 – 5/20/2011||503||37.8%||39.4%||21.1%||1.8%|
|5/21/2011 – Present||506||41.7%||34.0%||21.7%||2.6%|
Also, the balls he has hit in the air are carrying over the fence for home runs much less frequently.
|Balls in Air||HR||HR/Ball in Air|
|9/1/2009 – 5/20/2011||304||18||5.92%|
|5/21/2011 – Present||282||8||2.84%|
I’m not sure what has caused this change in Walker’s production. I checked out his spray charts, opposing pitchers’ pitch type selection, etc., but nothing jumped out as a potential cause. His swing also does not seem to look all that different to me than it did in prior years. Whatever the reason, Walker is now hitting the ball on the ground more often and struggling to hit the ball out of the ballpark. Unfortunately, this issue will significantly limit his value moving forward if it continues.
Stats current through Sunday’s game.