Dan Wiederer: Cassius Marsh’s taunting violation was the most costly and controversial of the Chicago Bears’ 12 penalties. So what exactly happened?

In the moment, Cassius Marsh thought little of it. He was on his way back to the Chicago Bears sideline Monday night, fresh off a clutch fourth-quarter sack, followed by a spinning martial arts kick celebration and a couple of seconds looking toward the Pittsburgh Steelers bench. His adrenaline was surging.

With the Bears trailing 23-20 with 3:16 remaining, Marsh had taken down quarterback Ben Roethlisberger for a 7-yard loss. The Steelers were facing fourth-and-15 and sending their punt team on the field. Marsh was headed back to his sideline. That’s when he brushed past referee Tony Corrente and felt jostled.

Again, in the moment Marsh thought little of that. “I thought it was accidental,” he said. “You bump into people on the field. It’s football.”

But within that mini-collision — a bump that