Illinois is not falling fast. Their 7 deep is basically 3 newcomers, (2 Fr and 1 JC) 2 So, 1 jr and 1 sr. Underwood is a very good coach, that will play a pressing style of defensive basketball that relates well to Chicago kids.
He took a team at OK St that won 12 games the year before and got them to the NCAA tournament in year one. He scheduled aggressively this year at Illinois, going to Maui and they also drew Notre Dame and Georgetown in the B1G/ACC challenge and Gavitt Games respectively.
If I were an Illini fan, I would be excited about the future and not at all discouraged.
Similarly, for Creighton, their top seven are 3 soph, 2 fr, and 2 jr. They will be fine going forward.
Sadly, the illini hired a coach with a system when they needed to hire a recruiter with a system. Underwood did the right thing in nabbing Chin Coleman to help with Chicago/Down South...but he is not enough which is why they missed on the top 3 in the state this year (Those guys went to Oregon, Kentucky and OSU)
They got beat, at home, by a super young/bad Hoya team that had no problem breaking the pressure and shooting 55%.
His team at OSU was fun...but also had a 1st round PG (Evans, I think he was a first rounder)