Stick with my current players or switch any of them?

Scoring is 1 pt for passes defensed and assisted tackles, 2 pts for tackles, 3 pts for sack, FR, INT and FF and of course 6 for TD.
We play one DL and two any D.  If I win this week, I make the playoffs.  Lose and I'm done til next year.

I've got Poz and DJ Williams, McCarthy, James Harrison and Kurt Coleman are all available.  Should I trade either of my two for any of the 3 available?

At DL, I've got Trent Cole & JPP.  Andre Carter is available.  Which of the 3 would you go with?