I do not think substance abuse is involved here. I knew Ced from the time he was a sophomore through his senior year and had him in one of my classes (as well as his little sister). I was also one of his class sponsors, so we got to know one another pretty well.
I find it hard to believe he would say that he wished he had not came to Tennessee, unless it was due to the loss of his family members that he missed out on time with, as someone else here suggested.
Ced was very concerned about what the people in Clarendon would think when he decided to break his verbal commitment to Houston Nutt & the U of A to become a Volunteer. I believe that the University of Tennessee was the best place for him, and (being the intelligent young man he is) I believe that he knows that was the right decision as he looks back at his college years....even though it did unfortunately lead to him missing time with some of the most important people in his life and that had to be very difficult for him.
I read the NY Times phone interview with his mother. Like her I find it hard to think he is "done" playing football. My personal theory is that Ced realized he wasn't going to get the playing time he wanted there after they brought in Jones and placed Leon Washington above him on the depth chart...just like (I believe...and this is pure supposition on my part) he realized he wasn't going to get the playing time he wanted at U of A. Some sources have said he was homesick, and that may very well be a factor. Ced is very close to his family, and they are a important part of his life.
Cedric, if you should happen upon this, I wish you luck in whatever you do. You have followed your dreams, and for that I want you to know that Ms. V. is very proud of you. I'll miss watching you on the gridiron, but I have faith you will do great things in this world. They say whenever a door closes a window opens, and I believe that. Peace.