While I am not one to call out players, and St. John's ability to work itself into deep holes at the beginning of halves is also a culprit, Chris Obekpa DID drift into the paint for absolutely no reason - no player was driving or even jogging through as a decoy, and Obekpa was on the Bluejays' most deadly shooter, Doug McDermott.
McDermott might have made the shot even if Obekpa came over the screen more quickly. But they left a future NBA player wide open.
And yes, that's probably an illegal screen. It's also a call that most refs won't make against the home team in the waning seconds of a tight game.
In fact, it inspired a college basketball watcher to declare this the "Year of the Buttscreen" - other players are getting around with... extending themselves on a screen (h/t Luke Winn's Power Rankings):
Alas, these things happen. A weakened Marquette team comes to New York on Saturday; if St. John's plays with the energy and concentration show on the road in Omaha on Tuesday, they'll be able to knock off the Golden Eagles.