Steelers - Bengals Referee Call?

By B. Carter

In the Steelers/Bengals game, receiver Paulson caught a pass and was stripped of the ball after a 30+ yard gain. Prior to either team gaining possession of the fumbled ball the official blew the whistle. After this the opposing team (Bengals) gained possession.

My question is why was the play not ruled dead after the blown whistle. The Steeler player did not go after the ball after whistle was blown so how could the play be changed "after" a blown whistle.