I disagree that Barnes is a poor game day coach. He prepares his teams pretty well for each opponent and doesn't toss aside the game plans when the team struggles to execute. When he has a lineup full of players with years in his system on the court maybe he will make more adjustments. Actually I thought that TN looked pretty well coached last year... they lacked talent and size. They hung close to most opponents... there were really only 2 or 3 lopsided losses.
Guys like Pearl and Tyndall are very animated during games, but their players seem no less confused or motivated than CRB's. Just because Barnes isn't a wild man on the sidelines doesn't mean that he's not communicating adjustments to his guys throughout every game. When he makes a substitution most of the time he'll talk with the guy that was just replaced. Bruce on the other hand put Tony Jones in charge of creating a scripted substitution rotation before the game even began. Tyndall stuck with his defense even when it wasn't working. He lived and died with how well the opposition was knocking down 3s and rarely deviated from his philosophy of focusing intense defensive pressure on everything other than the perimeter.
When Barnes had his transient 1 or 2 year players at Texas, he maybe didn't bother changing things up... he was living and dying letting them perform or not. He knew what he was going to get from them whether he was constantly pulling strings or letting them run with what he knew they were capable of.
He has a different philosophy on how to handle his inexperienced players on the court. That doesn't mean it's a poor approach. If he has 3, 4, or 5 guys on the floor with years in his system he might make a lot more drastic in-game adjustments. With the rosters he's had he probably knows it's best to keep things uncomplicated.