UTR is a bit like RPI in other sports.... decent analytic attempt to predict a match-up but it's far from perfect. If you look at Ohio State vs UNC in individual UTR ratings OSU is favored on 4/6 courts. The largest difference between players on the same court is at 2 where UNC is a sizable favorite. Power 6 is an average of a team's best 6 guys so overall UNC can have a better "Power 6" than OSU even though they're underdogs on a majority of the singles matches, albeit slight underdogs on all 4.
Doubles is also really hard, maybe impossible at the NCAA level, to evaluate with individual UTR. Then there's court conditions, weather, stylistic match ups, etc. Bottom line, everyone left is really good and there aren't a lot of gaps between the teams. Last year we were a dominant #1 seed on our home courts and we still had a really close call with the A&M semifinal going down to a third set on #6 singles. It wouldn't be a shocker at all to see a couple of upsets tomorrow.