There are a couple of reasons that I think cause our big men to get in foul trouble.
1. We are playing two freshman and a sophomore in the post and the fourth player is also a freshman. They make freshman mistakes. In many cases they are used to being able to dominate in the paint by virtue of their size and while that was true at the HS level it is no longer true at the college level. They will have to improve and with experience should.
2. Coaches of opposing teams know our tendencies. When we go to a zone they move the ball until they can find an opening for a guard to dribble penetrate into the paint. That forces our big men to help and they are now out of position both on the ball handler and to the opposing big men who receive the pass in the blocks.
As for Haws, he is a great shooter so he gets special attention from defenders. Are they grabbing and holding, yes. He still gets to the FT line a great deal. But one thing that he is falling prey to is allowing his temper to show on the floor. I know it is difficult but my guess is he is getting a reputation around the league. Opposing players know it and officials know it.
I also think Dave Rose needs to work the officials a little more. It does not get you much but it puts your thoughts in their minds.