What's the biggest concern for the TEXANS defense facing the PITTSBURGH offense?

The ability of Ben Roethlisberger to keep plays alive has always been an issue for the Texans defense. Big Ben has consistently created space and time to throw and that can't happen this week if the Texans plan on upsetting the Steelers. However, keep an eye on Le'Veon Bell as a pass receiver. In 2014, the last time the Texans faced the Steelers, Bell made the reception and run after the catch in the second quarter that broke the damn wide open in a win for the Steelers on Monday Night Football. The question for the Texans is which player makes the most sense to cover Bell in the passing game?