http://www.nfl.com/videos/nfl-game-highlights/0ap2000000312210/GameDay-Colts-vs-Patriots-highlights
Colts first TD you could say McCourty is late but unless you know the play call, you don't know if he's left his coverage once he's seen where the ball is going or if he is actually late. Dennard is in coverage
Colts big gain in the 3rd - Gregory is the safety on that side of the play, Dennard once again is in coverage.
Next highlight is a Colts TD - Gregory is in coverage and McCourty tracks back leaving his own coverage assignment seeing Gregory beat with the ball already in the air and makes a tackle, albeit in the end zone.
Nothing there screams "horrible" play by McCourty.