N=2 (me + adarq) evidence for why broad jump is completely useless w/r/t vert, dunking, whatever:
Before my ankle sprain I was messing around in between sets during a workout and broad jumped 9', or farther than adarq has ever jumped in his life, even at his peak. No warm up, just jumped. And yet I probably have the worst vert (definitely the worst running vert) on this whole forum at the moment, even without the sprain.