However, even when healthy, you have to consider the impact and strengths Sanders has an how it would change on a different team.
The Colts are a hard charging 1 gap team that asks its DL to blast through a gap worrying only about rushing the passer and maybe finding the RB along the way. Sanders ability to read the run play, and fill the gaps that are created by that style represents the majority of his contributions to that team. In essence he is the unblocked man that reads the play and runs to whereever he sees the play bouncing too.
He is tremendous at that, but in a system where that would not be his job, how much value does he have?
I don't think anyone is going to sign him based upon his coverage skills.
Teams that play gambling defenses that ignore the run and need a guy who can plug the holes created by their system would value Sanders a lot more than a team that plays a 2gap system and only asks the safeties to prevent 10 yard gains from becoming 20,30,40+.