Here are Matt Cassel's 1st 5 games as Brady's replacement in 2008:
13/18, 152 yards 1TD NE Points for Game - 17
16/23, 165 yards NE Points for Game - 19
19/31, 131 yards 1TD, 1INT NE Points for Game - 13
22/32, 259 yards 1TD, 2INT NE Points for Game - 30
22/38, 203 yards 1INT NE Points for Game - 10

Should NE have been looking for a different backup QB after those 5 games?