No Fordy, my point is, we need an extra cb because of the above. I have a feeling Kelly will remain Johnson's understudy, leaving Wilson and possibly Ayala (not convinced he'll remain, mind) as the youth players for the central roles. If we're ambitious Carra, Agger, Skrtel + one other and one or two younger cbs is what we'll need.
The easiest way to solve this is to keep Carra, Agger and Skrtel, then use Wilson and Ayala (and perhaps Kelly too) as backups for CB. It's still six options for two positions and that's more than enough. Allows us to get some new blood in (youngsters) while we focus our spendings for other areas of the team.
Fast forward a year. Next summer it's likely to be bye bye Carra, we'd know a lot about Wilson's and Ayala's qualities, the same is true for Agger's injuries. If Agger has another season when he can only play 50% of the games, we can't keep him. Then we use this information to replace those who are not up to it and we sign a new CB if we think it's necessary.
Personally, I'd want to be more aggressive and keep only two of Carra, Agger and Skrtel. I think Kyrgiakos' time is/should be up, simply because his role as 4th pick should go to Wilson/Ayala. And I want us to use our three promising younger CBs. Trust them. It's worked well when we've given the kids some trust.
If I was to bet, I'd bet on us keeping Agger, Skrtel and Carra for another season. This gives us plenty of options and we can sign players for other areas of the team this summer.