Hot take, but Illinois really should have built a new stadium instead of the remodel. Maybe it's for the worst (and you end up with a soulless multi-event geared place like Ohio State's Schottenstein Center or Oregon's Matthew Knight Arena), but keeping the Assembly Hall form factor really hampered any huge gains. And I'm saying this as someone who LOVES the Assembly Hall. Could be something to the PA and music stuff, but I'd argue the lighting is top notch (was completely revamped with the remodel).
Maybe the upcoming seating reshuffling helps things, but I doubt that too, because the closer seats are getting even more expensive (so more unattainable for the kind of fans there for passion rather than business purposes).
But really, the lull is winter break games. Illinois' main student populace doesn't live close to the stadium, so break games are extra dead.