As a dancer, I'd like to say that "musicality" is a powerful thing and when needing to coordinate or choreograph numerous people together, music is the perfect tool for that. You can have 32 Swans on stage all dancing in perfect sync without having to watch each other b/c they have the music that binds them and even when the music is not there, they have the sense and timing of the music in their heads and can count the music so they are still together.

Jackie Chan has spoken about how he has had some fantastic martial artists who just didn't work out on his stunt team because they didn't have the sense of rhythm and flow that was required for the choreography. Chan comes from a performance/dance background at the Peking Opera and so has an innate understanding of tempo, rhythm, and music and that shows up in the way he organizes and build his stunts and his action. When he sets up a fight sequence, the other fighters have to have that same kind of musicality (even though there is no music).

On the football field, coordinating QB steps to WR steps or WR steps to another WR steps is similarly demanding and could benefit from the unity that music provides, especially a very familiar beat or even better, a familiar and enjoyable piece of music. A WR can be thinking "12 steps, plant at 3second and break" or he could have "Smooth Criminal" in his head and think "12 steps, plant on "...OK" and break". You get all teh WRs running to "Smooth Criminal" and they should be breaking on sync'ing on the music together.

Counting music is a bit hard for most novices, but 4/4 time is really REALLY easy to hear and especially people that enjoy freestyling or just club dancing can easily feel the time. Having music playing as part of practice makes alot of sense and is another way that NFL/players can benefit from the world of Ballet/Dance. And it is very cool, imho.