That first quarter bomb was not all on McCourty. There was no one in the picture with him. He got beat, but there was no help anywhere. The third down pass interference penalty was a big mistake, but he battled hard throughout, helped out in run support, and made some nice plays later on.
This is a bit outdated and bound to change based on today's results, and it's from PFF which has question marks around it, but for what it's worth, Arrington and McCourty aren't as far apart as some posters think.
Targets: Arrington leapfrogs McCourty - New England Patriots Blog - ESPN Boston
McCourty has been targeted more in fewer snaps, and given up more catches (44 to 31), but Arrington has given up more yards total and per catch (497 to 185). The big difference is the TDs and INTs. If you take away the INTs, Arrington's QBR is 93 while McCourty's is 84.
Of course INTs matter quite a bit. When McCourty made a ton of picks last year, he was a Pro Bowler, but he wasn't a true shut-down corner like we all hoped. Arrington has made some great plays and gotten a few gifts, but deserves a ton of credit and has been the better corner. I'm just saying the difference is not as vast as some think.
And as for those who question PFF, that's fair. Then again, considering many of those same people also were confusing Ihedigbo and McCourty repeatedly today, I'm not about to put a ton of stock into their opinions that McCourty should be benched because he's the worst corner in the world.