Tired Legs in Centerfield

After Troy's article on Ellsbury's impending shift to left field, some feedback from our readers had some questions about some of the reasons for Ellsbury's decline in defense this year. Peter Gammons brought up a small story about how Rickey Henderson felt his basestealing affected his performance in centerfield.. yet no where else. Since it's the holiday season, I figured why not answer one of our commentor's question: Is their any data showing that excellent base stealers predictably decline defensively? Now, collecting this data is not the easiest study I've tried. Defensive statistics and qualification per position can sometimes be tough to obtain. Outfielders tend to shift positions more frequently, even over a small sample of years. Defense analysis is something I intend to look into more this year, but to start, here's a simple look at the past two years of "primary" centerfielders.