If there was any justice in the world Fergus McFadden would have the 12 jersey. He's been excellent for Leinster recently, far better than D'arcy anyway.
Fitzgerald could play there, but I'd rather see him on the wing while Earls is more of a 13 if he is to play in the midfield. Tommy Bowe could be put at 13 and Drico shifted to 12, but it probably wouldn't be a fantastic idea to move BOD to a position he's never really played in. James Downey is a massive outsider but probably merits a shot more than Paddy Wallace.
The only other options would be Eoin O'Malley (too raw, doesn't get enough game time), Darren Cave and Nevin Spence up at Ulster (both are really 13's) and Kyle Tonetti at Sale (can't see that happening). Don't see any of them being considered though

It's a serious weak point for us at the moment.
In general the team isn't as old as it is made out to be. Aside from the centres and locks, we're pretty youthful. Here's what I'd pick:
15) SuperRob Kearney
14) Tommy Bowe
13) Brian O'Driscoll
12) Fergus McFadden
11) Keith Earls
10) Johnny Sexton
9) Eoin Reddan (I dunno, why not?)
8) Jamie Heaslip
7) Sean O'Brien
6) Stephen Ferris
5) Paul O'Connell
4) Leo Cullen
3) Mike Ross
2) Sean Cronin
1) Cian Healy
There's a bloody massive backrow in there, could go toe to toe with pretty much anyone. 2,9 and 12 are worries, but I have a lot of faith in Fergus. Were it up to me, Donncha O'Callaghan would be 4th choice lock. I think he's been shocking this season. Ill disciplined, ineffective, not worth a place. Tuohy, Cullen and O'Connell have all been better, but I'd be shocked if O'Callaghan doesn't start. Steady Deccie eh?