I'm talking about last year.
Last year, I thought the corners were pretty solid. Outside of Kiffin deciding to try out Carr as a shut down corner against Garcon and Megatron and Scandrick getting isolated on Jeffrey in cover 3, they were pretty effective. Even Claiborne did well against the Giants and others when he wasn't leaving the field for the training room.
Most of the issues were Carter getting handled deep, Heath not being able to compete on completions in his zone, and Lawrence and Sims being complete unable to understand much less execute their assignments.
QBs had the middle of the field wide open from game 5 when Sims started playing regularly all they way though to the last two weeks of the season when Wilber had emerged and Holloman finally got healthy.
The defense of the last week against Philly, which while not great was able to get off the field at a decent rate, is what i use as the starting point for my expectations for the defense this year. They weren't good enough to overcome turnovers, but at least you had 7 guys in coverage who at least understood their assignments.