FWIW, at PSU he often ran 4-3 looks even against teams that featured 11 personnel. Last year I went back and watched the 2015 PSU/OSU game for reference, and he PSU was in 4-3 sets ~1/3 of the time, even when OSU had 3 WRS on the field (largely because he was hedging his bets that they'd try to run the ball on early downs).
So we know Shoop is willing to run 4-3 looks even against teams that try to spread out defenses. We just don't know why he didn't last year.
It could've been because he didn't like what he had to work with at LB (but if that's the case, why change jobs to begin with?), because of injuries (but, again, why didn't we see more 4-3 early in the season when the team was healthy?), because he was trying to ease the 2016 Vols into his scheme, or because Butch wanted didn't want him to change things up too much.
Either way, we know he has run much more 4-3 in the past than he did in 2016. It's hard to tell why he changed things up in 2016 and if that trend will continue though.