Is Nebraska for real. No.
When I saw they were 21 in the preseason rankings I actually had to look it up to make sure it wasn't a mistake. This is why preseason rankings are a joke. Nebraska got an 11 seed in the tournament last year based entirely on an 11-7 Big Ten regular season record that included winning 10 of their last 12 regular season games. They had wins @MSU and vs. UW in that streak to give it some legitimacy. Nebraska was obviously playing some good basketball during that streak, but a season doesn't consist of 12 games. Overall Nebraska was 19-13 (no other team in the preseason top 25 didn't have 20 wins last year, and almost all were over 25).
What Nebraska did have last year was an electric new arena that gave them a serious home court advantage. The new arena and the rowdy Nebraska fans were alive in every game I saw there, preseason or Big Ten. Nebraska rode that home court advantage to an impressive 15-1 home record (7-0 preseason, 8-1 Big Ten) including wins over UW and OSU. On the road or at neutral sites Nebraska was a woeful 4-12 (1-4 preseason, 3-6 Big Ten, and 0-2 post season). I don't expect Nebraska to be able to repeat their home court dominance this year, rowdy crowds or not. I don't know that they will be all that much better on the road though.
Nebraska looked god awful in exhibition against Southwest Minnesota State. Their offense looked unfortunately a lot like it did last year, which isn't good for a team that finished 272nd in points per game and 257th in FG%. Their basic sets resemble what you see from an NBA team playing the 2nd night of a back to back during an opposite coast road trip. Lots of one on one isolation plays from the wing, weak ball screens with no passing from the ball handler, and jacking up contested 3s. The defense wasn't any better. They mix man and zone but do neither well. The announcers kept saying how hot SMSU was from 3 but didn't mention once that every 3 was wide open. How hard can it be to contest 3s against SMSU?
Now that I have that off my chest, Nebraska is not a bad team, just over hyped. They did play better defense in the 2nd half, but the offense was still ugly.
Nebraska returns an experienced group including 6 of the 8 players in last year's rotation. It would have been 7 but Leslee Smith hurt his knee and will have to sit out. They also add senior graduate transfer Moses Abraham from Georgetown. There are 4 freshman, although only Nick Fuller got first half minutes vs. SMSU. 6'10" freshman Jake Hammond was ready to redshirt before the Smith injury, but may get forced into minutes this year.
Nebraska's preseason ranking is based largely on the return of 3 quality Juniors Petteway, Sheilds, and Pitchford. Sheilds and Petteway are wings that thrive on dribble penetration, and getting to the free throw line. Pitchford is a big that lives on the outside and gets open 3s off the wings penetration. They were all somewhat one dimensional last year. The wings can't really shoot (both barely over 30% from 3), and Pitchford who is 6'10" took over half his shots from 3 (hit 41%). If they are to be better than last year all 3 need to expand their games.
They are joined in the starting lineup by senior forward David Rivers and 6'4" sophomore guard Tai Webster to give Nebraska some decent size. They don't really have any post up game though despite having 4 guys 6'6" or taller and a 6'4" guard. In addition to no post game they also don't shoot 3s well, hence the horrible offensive rankings. Rivers isn't a perimeter threat (only 3 attempts from 3 last year) and Webster hit just 17% of his 35 attempts from 3. The only high percentage shooter is the big man Pitchford.
Nebraska has 2 point guards they can bring off the bench in Junior Benny Parker and Freshman Tarin Smith. Parker is also not a shooter (0-5 on 3s last year) and is limited to transition and penetration for offense. He is a pest on defense (all players under 5'10 are required to be called pests). Smith looks more like a true point but also looks too young to do much this year. In the front court freshman Nick Fuller will likely be forced into some minutes although he doesn't look ready to contribute. Transfer Moses Abraham looks like a goony space eater at best, and Hammond may or may not play at all.
I don't believe Nebraska will repeat their tournament run from last year, but they are good enough to be a bubble team and likely NIT team. Petteway, Shields and Pitchford are good enough to carry them to some big wins.