Ben Roethlisberger's ability to beat teams with the downfield passing game is dangerous. He has the second most deep completions in the league this year.
The presence of Le'Veon Bell out of the backfield for Pittsburgh adds an extra element to worry about for the Jets. Bell is second in the league in both targets and receiving yards out of the backfield. The problems the Jets have in the secondary could potentially open things up for the back. Think about how the Jets have needed to play safeties deep. They need their corners to provide big cushions. They have had to roll their linebackers to minimize throwing lanes. They have even had their linebackers go out wide just to throw jams on receivers.
This is going to open up room underneath for a guy like Bell to operate should the Steelers target him, and Bell is plenty capable of making big plays. He has 9 gains of at least 20 yards from scrimmage this year.