Well firstly a couple of accepted givens (by almost everybody). You obviously need some goalie cover, you need four centre halves, four central midfielders and four strikers. You need credible cover for each position on the pitch, and probably a few kids thrown in. If you want to win the title, you might even need a couple of "options and possibility" players who you can chuck on. Maybe even a Luis garcia type who can find the bus keys under the seat and move it forward eight yards.
So where are we, being sensible?
Goalkeeper. We have goalie cover, I'm going to assume the Brazillian bloke is alright. Reina is also absolutely top class, so no worries.
Right Fullback. We have Johnson on the right who we have to assume is going to be excellent. Cover wise we don't have IMHO anybody credible. I knwo you could say "Degen" or "Darby", but I would counter whereas they may become realistic options, they aren't currently able to fill in if Johnson is out for six months.
Left Fullback. We have Aurelio who is pretty good when fit, along with Insua who is a good filler, and Dossena. I'd say we're Ok there, as long as one of the first two remains fit.
Centre backs. We have Carragher, Skyrtel and Agger. We need another one, pure and simple. No ifs and buts, you need four centre halves, and that doesn't include 18 year old kids.
Right midfielders. We have Kuyt

Left midfeilders. We have Riera, along with Benayoun and Babel. I'd say we're OK.
Central midfielders. We have Masherano, Lucas, the new bloke when he's fit, Gerrard if we move him, Plessis, Lee Peltier, John Ostemboor and GYBS. I'd say we are a bit light, particularly given the fact that they new bloke gets injured occasionally and the fact that it's very questionable whther or not Lucas is good enough.
The support striker slot. We have Gerrard. We could also use Benayoun there, or Kuyt

Main striker. We have Torres. We also have the option (or indeed the possibility) of using Egg Nog, Voronin, or Kuyt

Now no doubt I've forgotten someone, but anyway that's broadly how it is. We need an absolute MINIMUM of a centre half and a striker/support striker.
IMHO the squad is very thin, is it anyones fault?