When Utah and TCU both became pretty good, we were clearly 3rd behind them both... I don't know if we would have done better than either program... although the Taysom years, if he doesn't have 3 straight season ending injuries those seasons could have been incredible.
I don't think there is any doubt that we'd be a better program today if we were in the BIGXII. I think we'd start to see a lot of the high level LDS recruits choosing us over Stanford and Utah.
I still believe that we'd be a better program if we joined the AAC... it's just my opinion.