A 15-year veteran, Dempster has pitched mostly in the National League in his career, appearing for the Marlins, Reds and Cubs before being traded to the Rangers in a deadline day trade. Dempster is the owner of a career 4.33 ERA and a 1.43 WHIP. In his brief time in the American league, Dempster posted a 5.09 ERA/4.08 FIP/3.86 FIP with 10 homers surrendered in 12 games. Notably, Dempster’s K/9 increased 7.18 to 9.13 in the switch from the senior to junior circuits in 2012, but his walk rate (2.34 to 3.26 per 9) and home run rate (0.78 to 1.30) also rose. Bill James projects Dempster to have a 3.74 ERA and a 3.71 FIP with 172 strikeouts in 2013.
Dempster is a notorious prankster, so I guess the extra half million over the standard Red Sox $13 mil AAV contract handed out this off-season went toward props for new pranks for Dempster to pull on his new teammates.