I see the Deone Walker selection as a statement by the Bills that they believe in their coaching and strength/conditioning process.
Deone has unteachable size, but needs to trade about 50 lbs. of upper body fat for 30 lbs. of lower body muscle mass and related strength (not that you can really trade one for the other, but you get the point).
The 450lb kid from Florida would be about two times that challenge.