I feel completely justified in expecting McKelvin to start by opening day in year 2, and expecting him to be a top-10 NFL corner by year 4.
My view is that this pick came at a position where the Bills already had 2 solid starters and a good nickel back. In order for the pick to be justified, McKelvin has to be significantly better than Greer. The above expectations are the only way for that to be the case, in my opinion, so unfortunately the expectations being put on the kid are pretty steep ones.
If he's just another Terrence McGee (in other words a solid starter), the pick doesn't make sense to me. He needs to be something special, or the pick was botched.