While Matt Kemp's league leading (and eye pooping) .942 slugging percentage for 2012 is impressive, the L.A. Dodger centerfielder has been consistently crushing it for more than a year now. Outside of Kemp, no player in the top five 2012 slugging percentage ranking is even in the top ten this season. In fact, of the other players in the top five from last year (Ryan Braun, Jose Bautista, Miguel Cabrera, Prince Fielder), only Braun and Cabrera are in the top 25, and just barely at 24th and 25th place respectively.
Part of the reason why Kemp's power numbers are so incredible is what he's done with fastballs. Sixteen of Kemp's 31 hits have come off fastballs this season, and seven of his ten home runs as well.
Since the start of the 2011 season, Kemp has just been ruthless against fastballs:
Kemp is currently seeing 44.2% fastballs, which is actually up from 43.0% in 2011; league average for a hitter since 2011 is 46.9%. Expect pitchers to start throwing Kemp fewer heaters as the season wears on.