Carragher is an absolute liability. The number of penalties he would give away at club level if he wasn't playing at the kop end with a weak ref is appalling. Back when he threw his toys of the pram for not being selected and retired was semi-ironically the only time at which he should ever have been considered for international duty, so really the notion of 'Jamie Carragher, England Defender' should have been moot from then on.
He's lost all of his pace, commits stupid fouls or lets people through as a result, and generally looks out of his depth against your average Burnley winger, let alone anyone England would face on the offchance they slithered out of their group. Better choices? Dawson, Upson, Shawcross, Rio on crutches, Ledley King with both of his legs amputated above the knees, a stationary foam training man.
As for Gerrard, he plays in a position where he gets noticed a lot but frankly he contributes nothing. His passing has been atrocious for awhile, constantly picks the wrong option, and his shooting has been dire even by Jabulani-era standards. Nevermind that he's a thug and a cheat, great choice of 2nd captain.
The only way to use him to his full potential would be to play a 4-5-1 with him behind the striker and hope he successfully dives for a penalty around the 85 min mark but that would make other parts of the field significantly less effective.
The only world class players in that team are Rooney and, much as it pains me to say it, probably Ashley Cole. There aren't many clubs or countries for whom he wouldn't walk into the starting position at LB.
edit: I'd have to disagree about Barry 'usurping' the midfield slot because that's where Barry plays where fit, and playing at the more defensive end of midfield isn't Gerrard's usual brief at all. Barry and Gerrard played in those positions throughout England's absurdly successful qualifying run, and the left-sided inside forward position is far closer to where Gerrard plays his best stuff for Liverpool. The problem is that accomodating him at all then unbalances the team as he's not a real winger. Barry had one of his worse games yesterday because England as a whole were so feckless that he kept wandering forward to try and start something, but as a whole he's one of the more assured starters. The way to rebalance the midfield IMO would be to drop Lampard or Gerrard, ideally both, keep Barry central and chuck an actual left winger out wide, or at least Joe Cole.