SS or C. But that might be considered blasphemy here.
No it isn't (and this is eggszactly the sort of crap that people want to say about the OWA consistently). Let me see if I can explain it to you in very simple terms:
Forget C or SS for a minute because those are defensive positions, m'kay. Now, the question should be this:
What *lineup* position can be upgraded? The answer:
#5 for sure, possibly leadoff. That is two positions right there. Does that mean they need another 2nd baseman because that is the person who bats leadoff? No. It means they need a leadoff hitter, so you can actually (and read very carefully okay so you don't miss it) *MOVE* the current 2nd baseman who hits leadoff to the #6 role (or lower). That means you can move the current #6 RF to #5 permanently (as they seem to have done already). So if you want to talk about replacing the SS and C, okay... fine. But are you wanting to replace them defensively and that would be kind of bad... especially at SS. But if you want to replace them because you want to replace the #7 and #8 hitters, then it is even worse and speaks highly to lack of informed opinion as to needs on this team.
BUT... if you want to replace SS and C, keep the same or somewhat similar defense, and move those bats to higher positions because they can actually hit, then let's talk. Who? Miguel Tejada? Michael Young? Joe Mauer? Cool. What cost? And then, who do you move out of the #3 to place one of those hitters in that spot, Lance Berkman? Are you really wanting to do that?
So like Taras said... let's hear it?