I disagree. I don't think there ever was a real "window of opportunity" , at least by some of your definitions. Our S16 run was a flash in a pan, a S16 run doesn't launch a program to another level. I really agree with SanfransicoPete here, a S16 run will help with recruiting, and I believe it has, with Warren and a few others coming here, it possibly affected Sam M. decision as well, but I think he would have come regardless. I tournament run affects recruiting. Les is a pretty good recruiter, and I expect him to continue to improve in the future. This year would have been a great one, but with everything that happened, including losing 3 players last offseason, really determined the outcome.
Look at Illinois after their championship run in 2005. They were not able to act on their "window" because they really had none. I think in order to have a window you have to have a couple things. 1) Good established national name recognition, 2) Facilities to recruit with, 3) A coach that knows how to build on success. Weber should have been signing impact freshmen with lots of talent in 05-06, but did not, whether he just doesn't have the recruiting prowess or if he just picked some kids that didn't pan out to expectations.
Now, as far as Bradley getting a real "Window of Opportunity". We need to do several things-
1) Finish our facilities - In my opinion this has hurt our recruiting efforts many times, especially in Les' era, players keep wanting the best of the best. A programs success is a direct result of recruiting in the majority of teams (exclude Drake's team this year here, although they have some great players)
2) Solid recruiting by Les - not so many JUCO's anymore, real programs are built on 4 year players. 2-3 Juco's a year is fine, but not 5.
3) Make some real noise in the MVC
4) Get back to the NCAA's consistently. Like SIU consistency over the past 8 years.
If we can complete these steps, a true "window of opportunity" will open, and then the program may have the ability to get to the next "level".