Barnes doesn't build or assemble teams for tournament play, he builds a regular season roster that is what it is, it looks essentially the same all season and regrettably, the team does not improve much as the season progresses, his players make most of their improvement in the offseason.
It's not that Barnes is a bad tournament coach, he may be, from my seat the gist of the problem is his roster and player skill sets are the same in March as they were in the previous November, not geared to score in bunches, not prone to make a big run or blow anybody out of the gym, certainly capable of giving up a big run and having a hard time with the speed of a tournament team in the college game, such that the ability to win night in and night out or prep for a next day tournament game is often unattainable. FAU fully demonstrated all those weaknesses and shortcomings in a Barnes coached team Thursday night.
Texas is celebrating their first return to the elite eight since 2008, which is the last time Barnes was there as well and it is no coincidence, aside from last year's SEC tourney title over A&M, that he hasn't fared very well in the tournament game at Tennessee either.