Rojo made two big errors: first, assuming even naturally fast guys can easily split 46 with no training...no, that is damn fast, and even the handful of guys who might have the innate talent to do so would need to lose the bulk/weight gained from their lifting programs, and work on a little endurance sprinting. I don’t think most football coaches have their teams sprinting further than 50 yards, and in fact you often see guys running out of gas on 80-90 yard touchdown runs.
Second, I don’t have the stats but it sure seems a lot fewer elite football players are running track in high school anymore... so many of them are 100% focused yearround on football, doing seven on seven leagues, specialized camps and skill tutoring, etc. Therefore a lot of these college football players don’t even know how to run a 400, much less have any interest in doing so. I am guessing most college FB teams, even the elite ones known for their speed like Alabama, Clemson, USC, Oregon, Florida State, etc would be hard pressed to produce anyone who could even split 48 these days.