I also don't think the offense did the defense many favors in the 2nd half of the UNC game.
Remember, the depth here on defense is not nearly where it needs to be. Rueben Bain is obviously a serial killer, but he's a true freshman, and he played I believe 64 out of 70 snaps against Clemson. I don't care how good a true freshman is, when you have a sustained program with elite talent at every position, 2-deep, they're not playing 64 snaps out of 70. But Bain has to, partly because they can't keep him off the field but also partly because there just isn't a lot of depth yet.
So what happens when you don't have a lot of depth on your defensive front? You have to stay fresh. What happened against Clemson? Miami held the ball for 37:30....Clemson had the ball for 22:30. That keeps your defensive front really fresh, which clearly they were in the 4th quarter and overtime.
But what happened against UNC? Well, the 3rd quarter you speak of, UNC took the opening kickoff and scored. Inexcusable, but Jaden Davis gets torched, and we're down 21-17. We hold the ball for about 2 minutes, and fumble. Defense right back on the field. But they actually get a stop! Bang! We're in business! Oops, interception on the first play, defense right back on the field, this time on its own 23 yard line. Touchdown. Now the game is slipping through our fingers, the defense is exhausted. So what do we do on offense? 3 and out in 2 minutes. Ballgame.
So the defense was inexcusable, no doubt. I just wish we could've seen what happened if the offense didn't turn the ball over on literal back to back plays in the beginning of the 3rd quarter.