The report is out. It was the air boss that changed the lanes of flight for the fighters and bombers while the show was going on, causing the two to collide as they went to their new positions.
The pilot of the smaller plane failed. He disregarded or forgot flight safety rules in regards to maintaining visual of planes and maneuvering.
He lost track of the bomber when banking as it got lost under his wing and due to momentum slid into the bomber. He should have passed BELOW the B17 and thus be able to maintain visual of the plane.
