Kelly Johnson was once known for his power and patience. Now he's know for his strikeouts. What happened?

From 2007 till 2009, Kelly Johnson was one of the more interesting sabermetrical darlings of the league. He was athletic, played a premium position, walked nearly 10% of the time, struck out under 20% of the time, and flashed some power with the seeming potential for more.

Via Jeff Zimmerman's tool, here are Johnson's swing percentages, compared to league average for his last year in Atlanta:

Against left handed pitching: