I'll get roasted for this (again), but the roster is not the whole issue here. Unless Barnes decides to evolve his coaching philosophy on offense, its just going to be more trying to fit square pegs into round holes by forcing players to fit "his system" on offense, rather than shaping his offensive system around his players' strengths.
Yeah, everything folks are saying about Barnes now is similar to what Texas fans said about him when he was at Texas. I lived in Texas during much of Barnes' tenure there and got to hear about this every year in March. His teams were always great defensively, organized, well coached, all that, but when it came to producing consistent offense, they struggled a lot of years. There was a constant narrative about him "coaching the offense out of players," thought I can't tell you what that meant, only that Texas sports media talked a lot about it while he was there. They seemed to bring it up every year come Big 12/NCAA tournament time. I have no idea if they were right or wrong, but boy did they talk about it a lot.
And even with that, I don't want a coaching change. He's elevated our profile in the sport, so, I mean, I think it's been a pretty great run even with the tournament failures. But I want to say Barnes has only taken a top 40 ranked offense to the NCAA tournament in one season at Tennessee - the Grant/Admiral superteam year. That's the only one. Superior defense wins you a lot of games, and lets you upset better teams at times, but come tournament time every team that's advancing can run their offense and score points. The tournament format rewards consistent scoring ability (and guards, but, also, consistent scoring). And if you can't do that, then sooner or later you're going to get behind against a team that can score, and you're done.
But even with all that, it's still true that losing Zeigler cost Tennessee a lot, too. They might have have had enough to handle their business with him running the point. A lot of dumb luck goes into the tournament. It's a shame we didn't get to see the Tennessee that played well most of this year compete in the tournament.