Worry my opponent will pick up Riddick?

So my opponent might pick up Riddick and start him against me. Should I worry? Should I try to outbid him? Or just hope Abdullah regains his starting role?

If I do try to pick up Riddick. I’m not sure who to drop? Id drop ASJ but I want to pick up a second defense, since I’m not playing the Chargers D vs KC. Should I drop Burkhead?

QB: Rodgers and Rivers
RB: Hunt, Kamara, McCoy, Freeman, Perine, and Burkhead
WR: Green, Baldwin, Funchess and Goodwin
TE: Ertz and ASJ (dropping for defense)
Def: Chargers

Do not drop Burkhead. I would rather get Riddick out of your opponents hands than pick up a defense. Of course I may be a little jaded because I had Abdullah all year and my opponent used Riddick against me for 23 points in playoff round one contributing to my loss, but his catching out of the backfield and running is just scary to me to leave on the table for someone else to use against me. Nothing has indicated Riddick will give the job back to Abdullah and the lions just look better with him Out there.

The Lions are very clearly a better offense with Riddick in and Abdullah out. It has taken all season for them to realize this, but they have a clear direction now: Riddick. He is a playoff maker or breaker. If you can shed some fat on your bench to pick him up, do it immediately.

What defense would you pick up that would be a better option?

Is this a PPR league?