First off, at the very *WORST*, Mike Bell = Jerious Norwood, Brandon Jacobs, or Michael Turner. He's a backup who might be worth an occassional spot-start against hapless teams, and who will probably become a top-10 fantasy back if the guy ahead of him goes down (a distinct possibility in all 4 cases, due to size and workload issues). If Turner/Norwood/Jacobs are rostered in your league, Bell should be too (I know there are some extremely shallow leagues where these guys aren't worth a roster spot).
At the very *BEST*, Mike Bell is still a shareholder in the Denver rushing game and could very easily still average 12+ carries per game from here on out. Tatum Bell might have been the #2 back in Denver, but he still finished as a top-24 RB. Same deal here, potentially. And if Mike Bell fails to live up to that potential... well, like I said, at the very worst he's Michael Turner v2.0.