Knowshon Moreno has all the potential to be a special back. In my mind, he is a quicker, less powerful version of Marion Barber. He's gifted, but has struggled to adjust to the speed of the NFL.
In Correll Buckhalter, the Broncos have a career back-up that would probably be a franchise back if he weren't dogged with injuries his entire career. He's a very fast, one cut and go style of running back who in all honesty, out-shined Moreno this season.
Peyton Hillis was a very effective runner for Mike Shanahan.
While Buckhalter has been a great addition to the Broncos, he is also an aged one, as far as running backs go. The injuries persist and you just can't trust that he will be on the field week after week.
Moreno struggled in finding open space most of the season. He tries to do too much by himself, and hasn't been a very patient runner, and has done his offensive line no justice by rushing things.
Hllis doesn't get any playing time, and I expect him to find a new home, possibly with Shanahan in Washington.
I have every reason to believe that Moreno will pan out and become a reliable running back. The Broncos can however, look to a huge crop of free agent running backs for help.
One guy that really sticks out to me is LenDale White, a kid from Denver that has found himself in a struggle to get any blow behind Super Star teammate Chris Johnson. He'd fit perfectly in McDaniels power running offense, and be a great goal line option for any team.