Gordon or Ekeler

Some background…I am in a 10 team .5 PPR league that can only roster 4 runningbacks.
My backs:
D. Cook
C. Carson
David Johnson
A. Ekeler

Today the Barkley owner dropped M. Gordon to pick up W. Gallman. Do I drop Ekeler to pick up Gordon? It will probably cost me $70 FAAB.