My guess is, neither blocking scheme works. But based on their talent level and endurance level, zone blocking at least give us some chance.
I think the fundamental issue of this football team right now is, what Lewis is trying to do, is a mismatch from the talent we have.
Little emphasize on the run <-> Good to great RB talent
RPO <-> pro style pocket QB with no running desire
Fast tempo <-> incompetent OL with only 1 summer training together and a QB who tends to hold ball too long and take the sack
We would be sitting at 2-2 right now if TCU has any tape on us. I know people hate me saying this but hey, truth hurts.
Right now we are running too many plays that require our OL to win one-on-one battles. We have very rudimentary running play design and we never really commit to it. Lewis needs to figure out something which might be different from his life long offensive principle. Because if he doesn't, we may not get to six wins this season. He has to adapt to our players' strengths. We have one of the best QBs in college football and many good skill players. There are plays designed to compensate for the OL talent deficiency. Do something that get the ball out of the QB's hand quickly. Try some quick slants, rollouts or bootlegs, whatever he can find.