Several points:
Jelks had already been moved to CB when he blew his knee out.
He did it returning a kick (not sure if it was a punt or a KO, but I seem to recall a punt).
Humphrey's progress made the move in both the team's and Jelks' best interest. Jelks wouldn't have seen that many reps behing Humphrey, but he didn't see it that way. Don't know what was in his mind, but I would guess he was blinded by the glamor of the RB position.
The move was somewhat controversial at the time, but Perkins mentioned that he was about to do the same thing when he took the Tampa Bay job. That quieted the controversy at least a little.
The blown knee truly was sad....Jelks relied on speed and shiftiness, and medicine wasn't near as far along in the treatment as it is today. So he lost that crucial half-step. In combination with not being truly mentally into the job, that was that.
Regarding the betrayal: He has expressed no remorse for what he did, just where the fallout landed him. As a fellow human being, I hope he finds peace and grace. Regarding forgiveness, though, I can't get there. Go your own way, Gene.