David Stockton, who fouled him "hard". But with Stockton at 160 lbs and Bronson at 270lbs, Bronson probably didn't even feel it. If the bulk had been reversed and Stockton was on the receiving end, he would have ended up in the 3rd row.

Physics and experience conspired against Bronson.

The only questionable thing I recall is Bronson kind of standing over Olynyk for a second like he'd just sacked him.