Ive watched ALL of Bells games in DEN, and i can say he will struggle at times when teams stack the line, But so will any RB, so who cares? Hes a solid RB with a good skill set and a really strong work ethic.
Shanahan got a little too arrogant with his running scheme a few years ago, and tried to take players and make them what they werent, like Bell into a FB. He also couldnt focus on one RB and instead got caught up in a random RB by commitee, but he lost control of it, and it was hard for Bell to stay focused and ready to be a RB again.
Bell will be fine, as long as he gets physically ready for the season.