If Luiz does not mature this season he may become cause for concern, but he is a talent, i would hope we can develop him further and keep him.

we r blessed with 4 great cbs. iva is a center back for me but good at RB. I have no fear of our center backs anymore. infact all of the defence have equal quality back ups. bertrand, azpi. we have a solid defence a fluid midfield and attack. but one thing I want to see is how we play going down to the big teams. I guess that's the one thing left.

luiz is a top top defender. worth nearly as azar and that says something about him. let's not be stiff about it let him do the samba a little. its in his nature and he has deserved it.

Luiz is still prone to some silly errors, which is to be expected, as he's still on a bit of a learning curve.

His natural position is a bit blured as he's played in a few positions during his career. At Benfica for example he started off as an attacking fullback , and you would think that would be a natural fit for him; comfortable on the ball; dribbles the ball out of dangerous positions (not always the best option as we saw yesterday)as well as loving to march up the pitch. He's been converted to a central defender so he's having to quickly learn other aspects of the defensive game which aren't so vital in other areas of the pitch; defensive positioning and decision making are obvious factors when playing centrally.

Time will tell , but the signs are good. Plus he still retains massive brownie points for his penalty in the CL

As for Cahill, have to agree with the OP, always looks solid in defence and when going forward.

He did learn instantly from yesterdays error though, as I saw many other times where he was in a dangerous situation and cleared it out

Luiz looks unfit to me. Seems heavier than last season too

Ivanovic weakest CB we have.
Ivanovic ball watches, lacks awareness, poor positioning and doesn't track runners. RB best for him.