Michael Cuddyer saw his slugging percentage drop 100 points from 2009 to 2010. The most obvious explanation for the drop would be the move to a new ball park, as the Twins abandoned the Metrodome for the outdoor splendor of Target Field. There is just one problem with that, as seen in the following table (numbers include the playoffs):
It's tough to blame the ballpark when the fall in slugging percentage on the road is the same as at home. Somehow, his power up the middle disappeared, as most of his home runs in 2010 were pulled down the leftfield line. In 2009, they spread into the power alley and centerfield.
You can see it in his slugging hot zones. In 2009, he dominated down the middle of the plate:
In 2010, that swath of power went cold.
His power was mostly down and in, the place to pull the ball. His doubles and triples stayed about the same, however, and there's no evidence pitchers worked him differently. It could be that at age 31 his bat slowed down a bit, just enough to keep those deep balls that used to go out in the park.