I'm an Illinois fan and this is an awful hire. If they were going to fire Bruce Weber, and it is no doubt that Mike Thomas decided he was going to do it in December, they should have found a guy better than the one they fired.
Groce is small potatoes. There is a reason why so many hot shot "lead recruiters" in big programs never become big program coaches. Illinois didn't need a recruiter, nor did they need a guy who could recruit Chicago. Bruce Weber was doing that just fine. They needed a guy who could coach up the talent available to get them to compete for Big 10 titles.
So what do they do? Hire a guy who, in his 4th year at Ohio (in a situation where all of the players are "his guys"), finishes in 3rd place in a one bid conference.