With it being a weeknight, I'm guessing the networks have to wait for "prime time" to begin on the east coast, which means games tip after 7pm. And in this case, they have to get in 4 games, so one of the "South" games slips to the later time slot.
ESPN is actually showing the West regional game as the latest game, according to this:
espn.go.com/mens-college-basketball/scoreboard/_/date/20160324
It's definitely a pretty late tip...the game will barely finish (assuming no OT) before midnight Louisville time.
