What? The Bulls having problems with physical play? Ever heard of the Bad Boys .. whom the Bulls had to get past in order to get their first 3 peat ... that was an era when hand-checking was allowed, and the Pistons put out a good old beatdown on Jordan.
The Knicks of the mid-90s were one of the most physical and defensive-minded teams you could play against.
You want defense? The 95-96 Bulls had 3, count 'em .. 3, guys on the All-Defensive First Team (Jordan, Pippen, Rodman). They embodied the tough defense that you're talking about. And oh, they won 72 out of 82 along the way.