Coaches are generally going to play the guys who practice well and who "play within the scheme". Most coaches need to have a "trust" factor that the players are going to do what is asked on a certain play.
Lavonte David isn't the only guy who used his athletic ability to make plays. Damon Benning has said on his radio show that Terrell Farley would drive the coaches nuts when he was at NU. Farley was a terrible "practice player" and was always doing "his own thing". Farley didn't start right away in 1995, but after a couple games of making big plays on defense, the coaches decided that they couldn't leave him off the field. It got to the point to where the coaches had to tell other LB's and safeties to alter their scheme to be a safety-net for Farley, because Farley was always going to freelance.
Some coaches are able to devise schemes that allow that type of "freelancing", and some coaches will want to force the players into their schemes. I am sure there are successes with both types of coaches.