The threat of Young as a runner helped open things up for Chris Johnson and others.
They average 4.1 yards per carry and 90.4 yards a game a year ago, when they ultimately turned to the immobile Zach Mettenberger as their starter.
Defenses have to be prepared for Mariota to take off at any time, with a designed running play, a zone read play, a bootleg that may turn into a run or a scramble. When a defense is working against an immobile signal-caller, it can neglect him as a run threat. That could be good news for Bishop Sankey, who was expected to make more of an impact than he did last year. The Titans O-line also struggled, which didn't help. Sankey is ranked just 40th on our list of RBs and is available as late as the ninth round in drafts.