While Horton does not lack in this department, Haley is the prospect that really has this trait covered. It is hard to play a physical game if you don't have the fire in your belly.
Horton's strong suits are being able to think on the fly to make on-field adjustments, and to totally immerse himself in preparation to take on a particular offense. I did note, however, that his teams are not great tacklers. Many will simply not hit, and those that do, seldom wrap up the ball carrier.
I don't believe that Haley has as yet consented to participate in an interview, but it is clear that Michael would like to get that opportunity. There is a good history between the two, and Haley did light the fires in the belly of the offense.
So far as ability to identify a player's strengths and weaknesses, and to then coach to his strengths, Gruden, Horton, McCoy, and Haley have all shown the ability to do that. (That was Whiz' biggest drawback as a coach in my opinion).