It's nice to have a nifty offensive scheme, and exciting to watch. But a team can't play offense without the ball. Last year during the off-season, Hoiberg often mentioned the need for improving at defense and rebounding. Maybe this game will be the impetus to actually make an improvement in rebounding. It's been mediocre for three years now.
As a number of posters have pointed out, the rebounding fundamentals are just plain missing, or if not missing, not being exercised consistently during the game. It was apparent all season, but nothing was done about it. Perhaps the defensive rebounding percentage stat that was always trotted out whenever the rebounding issues were discussed here created an illusion that the problem wasn't there. The Big 12 was down as far as interior play this year, so that may have also masked the problem. However, the rebounding problem was on display for all to see today.
If Hoiberg doesn't know how to fix it, he needs to hire a coach who can. It also seems that there are some game preparation and player focus issues facing the coaches as well.