I know that a lot of people think that, but he gets beat by every team's #1 receiver or #1 option on a specific play consistently, not just by a few guys. He plays with very poor technique, too poor for an NFL CB and he's too small/brittle to be a FS. They play him too far off the WR in order to hide his deficiencies, but that also leads to a lot chain moving catches in front of him. His saving grace for the ND team and what's led to his most vocal defenders has been the INTs. However, most of those were very bad decisions by the QB rather than really good plays by Gray.
He's a guy. A body at CB. Not good, not bad, just a guy.