.5pt PPR - QB Starter: P. Mahomes or R. Tannehill (1 Viewer)

I cannot decide who to start in a big playoff game this week. Tannehill, or Mahomes. I picked up AJ Brown off the waiver wire, and i am trying to figure out whether I should hand-cuff him to Tannehill, or start O. Beckham instead. Any advice would be greatly appreciated!