KC plays SD and Oak during those bye weeks and they are good run defenders.
Pittsburgh plays Baltimore and GB...although apparently R Lewis is hurt along with E Reed
SF plays TB and NYG
Foster is hurt and plays Minny and TB
Bennett is hardly seeing any time and plays Carolina and Detroit who is suprisingly good against the run.
I think you have to choose between LJ, Bettis, or Barlow. And of those three I think LJ offers the best potential reward, although Barlow is the safer bet.