Pat Burrell's move from the Rays to the Giants seemed to help his batting stats. He posted a .202/.292/.333 slash line with the Rays, raising that to .266/.364/.509 with the Giants. Looking at his performance against the fastball with both teams, however, I would venture that the improvement might have been skin deep.
First, look how Pat performed against various fastball speeds in 2010.
This graph shows that Pat could hit a slow fastball well, one in the high 80s. His in play average also went up on very fast pitches, but he saw fewer of those. Now looking at a time line of the 2010 season, look what happened when Pat arrived in the National League:
During his time with the Rays, the fastballs he saw were fast. When he started with the Giants, he tended to see lower speed fastballs, and he hit those well. As time went on back in the NL, however, he started to see speeds similar to the AL, and his average on balls in play took a hit, not recovering until the end of the season.
Pat hit .338 for the month of June in a Giants uniform, getting on base at a .405 clip. He hit .246 the rest of the way with a .352 OBP, his ability to draw walks keeping him valuable. It certainly looks like Burrell can't catch up to the heat anymore, which is why we may see Brandon Belt playing for the Giants sooner rather than later.