I think it's really hard for college players to deal with pressure. It's hard for anyone, but they aren't seasoned enough, and one and done is a pressure cooker - especially when you're ‘supposed’ to win. Not taking anything away from the Harvard players, but there's always more pressure on the higher seeded team.
I was very young at the time, but I remember DePaul (Chicago) finishing the season ranked number 1, and then losing in the first round of the tournament on more than one occasion.