I personally think it had to do with the "rules" of the seeding. If you take, Nebraska, Iowa, Xavier, Providence,Dayton and TN to be considered as 11 seeds, you are faced on how to match them up.
On paper you'd have to put TN as the favorite of course...but I think this is what happened.
Providence CAN"T be considered as a play in team.
Dayton COULD have been but the committee didn't want to give them home advantage.
That leaves Nebraska, Iowa, Xavier, and TN as the left overs.
Nebraska and Iowa were in the same conference. Overall - Nebraska has a better conference record, so would have an edge.
They probably placed it like this at first:
TN
NEB
Iowa
Xavier
TN and Xavier played each other. And by rule, they couldn't have been matched up together in tourney.
Same as Nebraska and Iowa. They can't be paired up.
And even Iowa and Xavier. They had already played.
They could of paired it like Nebraska vs Xavier and TN vs Iowa.
But they considered TN, Nebraska, and Iowa as better 11 seeds based on the conference. Power schools. and toss Xavier in the mix into a 12th seed.
Nebraska and Iowa can't play each other based on rules and leaves TN as the the one that's tossed in the Play-In game.
It could have been TN vs Neb or TN vs Iowa now...
But because Nebraska was higher in Big TEN they get the better bid.
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That's just how I viewed.