Give them time. Not everyone starts out as an NFL starting corner as a fresman. They have the athleic ability-- they just need the technique and the game time.
Also, if I remember correctly, McChesney played more consistently than Wilcox did, and is one of the fastest players on the team, and he beat Hadley and Shelton for PT. The fact that you're giving Wilcox the benefit of being able to progress into a serviceable starter and not McChesney isn't fair.