Per Adam Schefter:
Can't imagine Indy wouldn't have offered to match that deal if they thought Sanders had anything left. This news should confirm the reason that Indianapolis cut Sanders: they firmly believe he's damaged goods and are attempting to move on. That Sanders couldn't land anything better than this one-year deal despite visits to Jacksonville, Buffalo and New York does not bode well for league confidence in his ability to stay healthy.
That said? As long as it doesn't harm the Colts, I wish Sanders the best in San Diego.