Deep RB - Darius Jackson, Darrel Williams, Damarea Crockett

Dynasty 0.5 PPR superflex. I have Zeke as my RB1 and I also have Tony Pollard, who sounds like the third down back. Darius Jackson is fighting for the snaps if Zeke holds out against Morris (another team already has Morris). Which two of these four should I have on my roster? I have Pollard and Crockett while Jackson and Williams are free agents.