It does seem like a lot fo you think Carra is pretty close to being washed up. I would be intersted to hear what people think Agger brings to the table as a defender? It seems that the first thing everybody talks about with Agger is his ability to bring the ball out of defence and start attacks which I find a bit strange because surely the most important thing about being a defender is defending? It's very rare that anybody talks about Agger's defensive qualities. For those advocating a Skrtel/Agger partnership I think we would die a death from a leadership/organisational point of view if that was to happen. Both players let Carra do ALL the talking and don't forget we've got young full-backs at the club who will need guidance all season long.
If we sign Enrique, then him and Johno will be our starting fullbacks - plenty of experience in those two, so I don't think the need for an experienced leader is quite as urgent as Pepe, Gerrard, and Luis will all lead on the pitch with their performances. What we really need IMO is for one of Skrtel or Agger to step into the role of defensive organizer. I will touch more on this later.
When people talk about Agger being a ball playing CB, they focus on his ability on the ball because they are uncommon among defenders. It isn't because he hasn't got the skills necessary to be a good defender such as marking, positioning, tackling, and strength. He has all of those things, but also brings much more to our back line such as good pace for a CB, good ball control and distribution, great composure while in possession, and a shooting threat from distance.
If you are going to bag on one thing with Agger, it can only be his injury record. It is hard to justify building a defense around a player who seems to be constantly injured, but he is such a fantastic talent that it would also seem silly not to build the defense around him.
As for his partnership with Skrtel, I think it would be a bit rocky in the beginning as they would need to adjust to playing alongside one another, and would also need to determine who is going to be the one to organize the defense and keep everyone on the same page. This sort of thing can be learned very easily, but will take a few months to a year to get it to be second nature, but it is something we need to start preparing for sooner rather than later in my opinion.
In addition, I think Skrtel and Agger compliment each other very well as a CB pairing. Skrtel is a no nonsense defender who will attack the ball. He wants to win the ball, and his biggest downfall is that sometimes he is too aggressive and makes rash challenges. Agger on the other hand tends to be a bit more composed, and uses his positioning and timing to intercept the ball at or make a challenge at the right moment.
Bottom line, I think that this partnership can flourish given time and the proper instruction from the coaching staff. It won't be perfect on day one, but I think it could be great in a year.