Here Ken Pomeroy explains a little bit more about their ranking, which is much higher than would be expected given their seed and record. Since the tournament has started, they have moved their ranking up to #6 and are favored over us at about a 55-45 percentage.
The jist is that when Tennessee wins they blow out their opponents and when they lose they lose in close games, which translates to a unexpectedly high kenpom ranking.
Another note, which is relevant due to some of our slow starts,
"They (tennessee) punch teams in the mouth and walk away. In the first 10 minutes of games against SEC teams, they outscored their opponents by an average of 5.3 points. In the first 10 minutes of their 12 SEC victories, they outscored opponents by an average of 8.8 points. By contrast, SEC juggernaut Florida, which won each of its 21 games against conference teams, outscored opponents by a less-impressive 3.5 points per game in the first 10 minutes."