Paul Johnson was a master at changing blocking schemes on the fly. As a DE or LB you might be blocked by a different guy on the next play than the last one, or you might not be blocked at all. Like every other scheme, as the talent on the opposing defense improved, the scheme was less effective. It was also became easier over time for opposing coaches to prepare for since they had seen it over and over. That's one reason it was more effective at an independent (Navy) as opposed to playing a conference schedule. There are reasons why no P5 program runs that offense.
GT 2020: When you are starting a FR QB, a FR OT and a FR RB, with limited practice time, it's hard to throw a lot of wrinkles into an offense. Getting the basics down in hard enough.