With all due respect, if you're referring to a window of true national relevance (i.e. frequent NCAAT appearances in mens and womens basketball, frequent bowl games, frequent conference championships, upgraded conference, somewhat regular national top 25-50 rankings), the window is long closed. You could argue whether the window was ever open at all.
UB does not have the donor base, the state funding support, the student support, the brand recognition/media market, the athletics cachet of a program that can sustain success and move up the ranks. The "Haves" in college athletics are consolidating, and UB (along with every other G5 school, and truthfully many of the bottom-feeder P5's) is on the outside looking in.
That doesn't mean we shouldn't strive for success. UB should absolutely have an NIL collective and solicit donations, and UB should have the resources to be a contender in the MAC in all sports. But the Tilman Fertittas and T Boone Pickenses and Phil Knights of the world don't grow on trees.