IU usually beats the teams they've beaten so far this year. It would have been a major step toward reaching the NCAA tourney if they had beaten UConn, Auburn, or Kansas.
The 2-0 Big Ten start is good but in my mind this is the worst Big Ten in the past 40 years. I think Indiana may need 13 wins to make an at large tourney bid, and that would include getting a decent road win or two.
Nebraska is one of those because if you look at the schedule, there is a stretch where IU is likely to lose several in a row, and there is a stretch where they are likely to win several, but in terms of quality road wins, besting Nebraska would help.
From what I've seen of the conference this year, I would not be surprised if only 4 teams make the dance. Certainly things could change, but the league is terrible. We all will know how SMU feels every year by the end, where 4 or 5 losses in a mediocre conference isn't good enough.