In an article published on November 20, Rich Lederer of BaseballAnalysts.com mentioned that Jason Bay’s “power has been gradually drifting from left toward right field over the past couple of years.” He provided Bay’s hit chart at PNC Park in 2007 to support this idea. This interested me, so I decided to dig deeper into Bay’s hit charts from the past three years. If his poor 2007 season was the beginning of a quick career decline as opposed to a random down year, the cause would likely be diminishing bat speed. That would decrease Bay’s power, and consequently his value.
I went through each of Bay’s hit charts from 2005-2007, with the goal of examining the direction of his power. I tallied the number of balls hit to the warning track (in a rudimentary attempt to smooth out the effects of playing in different ballparks) and recorded the direction of the hit. I used seven different directions: left field line (LL), left field (L), left-center field (LC), center field (C), right-center field (RC), right field (R) and right field line (RL). The following is what I found:
As you can see, the number of Bay blasts from right-center to the right field foul pole has dropped only slightly over the past three years. He had 19 such hits in 2005, 17 in 2006 and 15 in 2007. The area where his power decreased dramatically was the left side of the outfield. After sending 40 hits in that direction in 2005 and 37 in 2006, he only produced 20 in 2007. In addition, Bay hit only four balls beyond the center field track in 2007 after 17 the year before. I also glanced at the rest of his balls in play at PNC Park over the past two years, and it appears that there is a general left-to-right shift in all other areas as well.
It is possible that there are other factors involved here. For instance, Bay may be making a conscious effort to hit the ball the other way. This is something I have hoped to see from him since he joined the Pirates, as he has plenty of power to conquer the Clemente Wall. However, it is more likely that this is something out of his control.
This is more discouraging information regarding his future performance, but Pirate fans can still cling to the hope provided by how quickly Bay fell apart. He was fine on June 3, but seemed to forget how to hit the next day and never recovered. I wish I had access to hit chart splits, as it would be interesting to see how often Bay pulled the ball during his second half slump compared with the early part of the season. While it appears from these numbers that his bat speed has declined, it is highly unusual for that to literally occur overnight. Bay’s ability to generate power to left field in 2008 will likely dictate his chances to recover from his disastrous 2007 season.