Not trying to put words in Vince’s mouth, but I doubt that he really means concentrating on pushing during top speed and speed maintenance portions–of a 100m. But 40 yards is different, and in my mind, if you’re going to accelerate longer, then you need to push longer. I doubt that a lineman has the speed to accelerate for the whole 40 yards, but it does not mean becoming vertical at 20 yards if you’re trying to run 40 yards FAST, for which a good sprinter is going to stay down and accelerate the entire distance.
The idea of having team sports athletes practice accelerating with sleds seems like a good one.