Nah, I didn't mean just the colts - I meant the league. Actually I think Albert Haynesworth might have even a greater impact on his team's defense than Sanders, but he wasn't on the list.
My justification for this is look at those two team's defensive stats when Sanders and Haynesworth play vs. when they don't - the colts get absolutely gashed by the run, and their pass defense is nowhere near as effective when Sanders is out, while the Titans fielded a top-10 defense when Haynesworth was in, and were just awful when he was out.
Like I said in my above post - there are certainly players out there that might be more physically dominant (Jared Allen, Brian Urlacher, Ed Reed) but those guys don't have a similar galvanizing effect on their defense, in my opinion.