The corners who can excel in the cover 2 aren't always the flashy types like Atlanta's D Hall or even Clements, so that may be why they're sometimes devalued. But, like you said, it's not correct to say that corners aren't important in the cover 2. They have to have good recognition skills, be athletic to cover a lot of ground, and they have to be physical. Guys like Penn State's Alan Zemaitis, now a rookie for Tampa Bay, are ideal for that scheme: athletic (the guy has a great vertical leap), good football skills, and tough enough to handle run support.