Connecticut and Arizona can credit their surge to the Elite 8 on their offenses peaking at the right time.
Net Efficiency Margin offense (blue)/defense (red) splits (all charts here are 5-game running average NEM)
While Arizona had a mid-season offensive mini-peak in February, Connecticut's offense was above average but relatively stagnant after their fast start in Maui. Beginning with their loss to Notre Dame just before the Big East tourney, the Huskies have averaged 23.8 offensive NEM with no game below 12. For some perspective, a team averaging 12 offense NEM would rank around 25th nationally.
Connecticut has outpaced the Wildcats defensively all season and so far in the tournament, so I'd give the slight edge to the Huskies. Of course, the way Arizona shredded Duke's top ten defense in the second half Thursday, their own defense may not matter.