Quad 1 victories include home victories against the Top 30 NET teams so the Purdue victory seems safe. At this point in the season, you basically are what you are, like the GPA for a student whose reached their senior year. The victories can still help and the losses will hurt, but the weight of each win or loss is going to have on the overall NET rating is not going to have the same fluidity that something like AP and Coaches polls might have that are more opinion based. Purdue is still in the top 5 in the NET ratings. Perhaps, if they had a string of QUAD 3 and 4 losses, it would put a bigger negative dent on their NET rating but they don't have that negative opportunity on their remaining schedule. If they lost all their remaining games (which they won't) they would still be 24-8 before the tourney selection, which is still a pretty good (.750 winning percentage) and perhaps still a Top 30 NET rating.