Last year's Xavier game between two very competitive teams at MSG only drew 6,600 to MSG. Last year's Butler game only drew 5,600 to CA, albeit during winter break. I'm not sure you could have predicted the rapid rise of this year's X and Butler teams but you can't question the fact that you've never met an alum of either of these programs.
To be fair, 5,600 is a sellout at CA. The place was sold out for that one a week in advance.
Forgot they reduced the seating in the "renovations". PS Butler did only draw 7K to the Garden in 2014.