When going for it on 4th was rare, the defense would have to adjust on the fly. Now they expect it and actually spend time scheming against it. The odds of success will drop simply due to the fact that the strategy is becoming common place.
Add to that the fact that BYU in particular shows absolutely no innovation on 4th and you get the results.
If analytics are king we don't even need to have a coach, a grad student with a ipad would suffice.