Guru advice needed for playoff run

Mr Guru sir,
My defense lineup has been questionable all  year.  Seems like I've been chasing players who never quite produce.
Here's what I have:
DT  Nagata
DE JPPaul
LB  Luke Kuechly
LB  Collin McCarthy
CB  Aqib Talib
CB  Buster Skrine
S    William Moore
S    mark Barron
DP  Perry Riley

I had Bruce Carter, but I'll likely drop him since he's probably out for the season.
I have Leonard Johnson (CB) on the bench

Who needs to go?
I'm kind of stuck at DT/DE since those positions are hit and miss, and I've got two good players.
Seems like Talib and McCarthy must go.  Also Barron...?
Will Talib produce?  I can play Leonard Johnson instead...just so hard to know.  I thought Johnson would produce big vs. Atl, but he didnt...tho 7 tackles is decent.

What's available on the wire:
LB  Burris
LB  Zach Brown
LB  Erin Henderson
Who's best to replace Carter?

As for my Safeties, on the wire is:
S Landry

And for CBs, I guess my question is:
Talib or Johnson, or play matchups with both?

Any obvious drops/pickups?  My offense has carried me so far this year...but it's defenses that win championships  :-)
I can only think of one week where my defense really showed up....tho maybe I'm panicking and there's no need to...?
  Any help is appreciated.

I'd pickup Zach Brown for Carter, Landry for Barron. I'd play the matchups with Talib and Johnson.

Awesome.  I didnt get this message before the WW, so I went with my gut and picked up Landry and dropped Barron.
I got to thinking about Brown and went with Anthony Spencer instead.  Spencer has been hot lately, and with Carter out, he should do even better...or do you think Brown is the better choice.

Thanks Guru!

I don't necessarily buy that he will do better with Carter out. I'm a diehard Cowboys fan and watch every snap. Spencer is a very good run defender but tends to slack off sometimes in rushing the passer which leads to his inconsistency. He has a good matchup, but I'd prefer Brown against the ball-controlling Texans.