Is Nebraska really running an up tempo offense?
If by "up tempo" you mean "no huddle", then yes, the Huskers are running an up tempo offense.
But if you go back to last week's Michigan State game, you saw a Nebraska team that walked up to the line, then waited for the play call. Taylor Martinez would clap his hands and then look to the sideline. More waiting. Then Martinez would walk around barking out a play call, then step back, clap his hands again, and the center would snap the ball.
Most of the time the ball was snapped with under ten seconds left on the play clock.
You'll excuse me if I don't consider that up-tempo. "Up tempo" would mean that the team isn't constantly waiting for a play call, but would be lining up and running a play immediately, possibly before the defense had a chance to get themselves in order, get ready for play.
"Up tempo" would mean that Nebraska is running more plays per game than most other teams. That's not the case either. Nebraska is ranked 47th nationally in number of plays run this season with 659. Compare that to UCLA, 13th nationally with 735; Oregon, 12th nationally with 739; or Louisiana Tech, seventh with 763. Ranked first is Marshall at 806 plays so far this season.
Fans might respond that since the team didn't huddle, that the defense doesn't get the chance to substitute, and they'd be partially correct. If Nebraska doesn't substitute, then their opponent doesn't get that chance. However, by rule, if the Huskers substitute, then the defense is allowed a chance to substitute before the ball is set in play, so there goes that advantage.
Up-tempo teams don't worry about time of possession. Marshall is ranked 102nd nationally with 28:02.67 per game in time of possession. Going through that previous list you have UCLA at 42nd nationally, Oregon 101st, and Louisiana Tech at 105th. Nebraska is 60th.
Now, granted, the number of plays per game and time of possession are affected by the opponent's defense, your defense, and your opponent's offense, but in a simplistic fashion, they indicate that Nebraska's offense isn't all that up-tempo, again, unless you solely mean up tempo to mean that the offense isn't huddling.