Never get too wrapped up in the preseason. The wins and losses are meaningless. Players are being rested for health, and coaches are all trying out new schemes. In 2014, DeMarco Murray managed just 52 yards on 3.7 YPC in all of the preseason. He was projected to play second fiddle to Joseph Randle. Murray went on to win the rushing title that season with 1,800 yards on 4.7 YPC. Joseph Randle is no longer in the league.
So, sure, preseason storylines can be misleading. Guys that look like nothing can be the next stars, and guys that look like sure things can end up third strings.