I'm not sure exactly who will be in the top 25 later today, but the only definites are Arizona and Purdue. I suppose it's possible that George Washington and Dayton could sneak back in with Utah, Cincinnati, and Baylor likely to fall out.
For comparison sake, though, the ACC has just five wins against teams ranked currently in the top 25 (the Big East has four), and that conference is 50% bigger than the Big East.
It's kind of a flawed argument, anyway, since beating teams in the top 25 or on the cusp of the top 25 is likely to keep those teams out of the top 25. You could deny UConn's tournament candidacy by making the same argument ("they haven't beaten anybody in the top 25"), but really, when you step back and look at it, they've only played one team (Maryland) that would be in the top 25 independent of their result against UConn. The difference between 25 and 50 being so small, it doesn't make much sense to differentiate between them.
That being said, I don't necessarily disagree with what I think is your primary point (that there aren't any powerhouses in the Big East). It's more than conceivable that five of the six bids from the Big East could be gone by the end of the first weekend, just like they were last year, and it certainly wouldn't shock anyone if they went 0 for the final 4 for the third straight year of the conferences existence.
But if there aren't any powerhouses in the Big East, there certainly aren't very many, if any at all, in the rest of college basketball, so that is a qualification hardly unique to the Big East. 'Nova losing to Oklahoma and UVA - one on a neutral court and one on the road - does little to expose them as a fraud, unless we're going to say the same things about Duke and Louisville.
With college basketball being as stretched as it is this season, all of the top leagues begin to look sort of similar. But the Big East is definitely in that first tier - along with the ACC, Big Ten, Big 12, and maybe SEC - while the American is in the third tier. Swap UConn out of the AAC and place them in the Big East, and that gap increases. By no means am I arguing that the Big East is a more viable home for UConn athletics, but at the same time, there is no sense in pretending that the two leagues are the same.