I think too much is made from these volunteer camps, if my boss said to me you have to go to a volunteer anything, it is no longer is volunteer...kinda duh.
Every year a good player gets hurt during these OTAs, we love it when star players buy into the system and show up, but most of them are there to mingle. CB is the position that needs this less than any, practice without pads allows WRs to show them up. Williams played on a very good defense and his play had a lot to do with the pressure the front 7 created. He's overrated, but I don't fault him for hiding it by not showing up.