According to BoydsWorld.com, there were 172 at-large entries into the NCAA post-season tournament from 2007-2011. Looking at the total wins, and calculated RPI (Boyd’s calculation, not the official NCAA RPI) we can get a reasonable picture of what it will take to be selected as an at large team.
The average win total of an at large team was 40.5, with a median of 40. Based on the histogram below, 40 wins equals a 50% chance of selection. 43 wins would be a 70% chance of selection. Currently, NU is on pace to win 34-37 games, which would give them about a 15-30% chance of selection. The last third of NU schedule appears to be a bit less daunting than the middle third, so 37-40 wins may be the most likely final result.
The average RPI of an at-large selection was 35 and the median was 27.5. This is the biggest hurdle NU faces with a current RPI of 71. According to Boyd, if NU goes 15-3 from today (17 Apr) their projected RPI will be only 45. Based on this histogram, an RPI of 45 would be only a 23% chance of selection. An RPI of >60 would mean less than a 10% chance of selection.
The next chart combines the win totals and RPI into a scatter chart. The red dot indicates NU's current RPI of 71 and a predicted win total of 37. At that point, it is well below most teams' win total / RPI combinations. If NU should get to 40 wins, its RPI would likely climb to about 50, which would put it just on the edge of of the selection grouping.
Can NU go 15-3 over the last third of the season? 13-5, with a couple of wins in the Big 10 tournament would also bring the Huskers to 40 wins. Even 40 wins, though, may not be enough as NU's biggest challenge is its RPI.