Butler got picked up by the right team at the right time. The Colts are young, have a great pass rush to help out their secondary and most of all had ZERO expectations to win this year. So they could let their young players develop and it was a pretty amazing year for the whole team.
With the Pats they needed immediate secondary help and could not afford to deal with the growing pains of young secondary players. He had a nice rookie season, but expectations were high year two and there were a lot of young drafted DB's and verteran free agents on that team. He had some tough games and they were quick to give the vertran players a chance to sure up their weak link on defense. It didn't help that the Pats had zero pass rush which crippled their secondary and the breakout rookie year of McCourty overshadowed any future potential Butler had with them.
