For the regular season, we over-performed. We had one of the toughest schedules in the country and won 26 games. We beat a bunch of NCAA tournament teams (including some very high seeds), won the Maui invitational, beat UNC at their place in a thriller and had a ridiculous comeback versus NC State. We played for the ACC regular season title in the last game of the regular season. The only bad showings were two bad losses (at Temple, Miami in OT) and a pair of big-margin losses (at Ohio State, UNC), although the latter amounts to style points more than anything else.
In the ACC tournament, we did OK. We didn't look great against Va Tech, but we won. FSU had a strong team this season. A close semifinal loss to them was not a great result, but was hardly embarrassing either.
We did enough to earn a 2-seed. I'm not sure what your expectations were, but earning a 2-seed seems like a pretty strong result to that point in the season. To argue that we underperformed is to say you expected a 1-seed, which seems ambitious after losing Smith, Singler and Irving. To argue that we should have garnered a higher 2-seed is nitpicking.
So about the only way one can argue that we underperformed is if the NCAA tournament is everything. We underperformed badly in the tournament, no doubt, but saying we underperformed for the whole season because of one bad loss seems myopic to me.