May not be related to topic. But rating NFL official this thought came to mind from the game I was at.
If I were a NFL DB coach, I would teach my DB how to tangle feet with WR's. I guess knocking someone down with you feet is not a foul.
I understand the "incidental contact", but if a WR is running down field a pass is thrown to him, that he probably will catch and a DB trips him. I think it should be pass interference. TMO