MJD for Shonn Greene

I got MJD on my bench and being offered Shonn Greene for him. Why do I feel like I'm missing something here? Yeah, MJD will be back this year, likely during FF playoffs, but will he even have an impact? Won't he be too risky of a start in the playoffs? Even though MJD has under-preformed this year, I'm hesitant to give up a (relatively) top tier RB.