Actually, McCourty's been playing really well as a cornerback this season. Here are his numbers according to Pro Football Focus:
#4. McCourty: (477) +10.3, 17 of 40 (42%), 264 yards, 2 TD, 2 INT, 6 PD, QB Rating: 65.6
He's rated as the 4th best cornerback this season, and was named to the AFC Pro Bowl roster on Pro Football Focus (
https://www.profootballfocus.com/blog/2012/10/23/pro-bowl-cheat-sheet-the-afc/2/). While he's obviously not a top 5 CB in the NFL generally-speaking, he's definitely a top 20 CB as of right now, especially when you take into account the fact that he has these stats covering the opposing teams' #1 and #2 wide receivers.
People need to stop hating on McCourty. They're dwelling on what happened last year (where he didn't get much safety help), and ignoring the fact that he's a good cornerback; in fact, he's the only good experienced player in the secondary we have (Dowling is on IR, Arrington sucks, Moore sucks, we haven't seen enough of Dennard, Chung is a liability injury-wise and coverage-wise, Tavon Wilson shows promise but is inexperienced, and Gregory is just ok).