"speed" is relative in football. As a former track athlete I can tell you that "top end speed" and "acceleration" are totally different.
We want football players to have great acceleration. Top end speed means almost nothing in football.
As a football player, you want to be able to run 20 yards faster than anyone else. How many times/game are you going to run more than 20 yards at one time?
It's great to evaluate 40 yard dash times, and that's a decent indicator of what someone's 20 yard time would be -- but it's not everything.
When you see Holliday from LSU running the ball, he looks SO much faster than everyone else because he's got the great ability to accelerate. He gets to his top speed faster than anyone else on the field. That's partly why he's such a great 100m sprinter, but on the football field it makes him really stand out. Demps from Florida is the same way.
So, no -- we don't need a speed coach. I think we should stick to recruiting fast guys to begin with, and then coaching them to play football.