So, it has to be either the 1-2 midfield or the inability of Gerrard, despite his great contributions to our attacking play, to play the role properly from a defensive standpoint. Is that a correct interpretation of what your saying?
Who else other than Gerrard is "not covering space or players" and therefore "not tacking/intercepting in front of our back 4"
Of the CM currently in our squad, who is "more defensively aware", and are there enough to make the 1-2 midfield work well enough to provide the proper defensive cover for our back 4?
Gerrard is our deepest midfielder. He has to cover the space in front of the back 4. He's in the team because he's great on the ball and at set pieces, no player can offer what he does on the ball. I don't think we have a player who can come in for Gerrard and be better defensively, Gerrard is as good as it gets, and it's not great. He can tackle though, more often than not he comes out with the ball. From what i've seen of Can he may be able to do this role, and he has the added attribute of physicality. Henderson and whoever else plays in the midfield, tonight it was Allen, it's not their job to cover that space or provide defensive cover. They're Gerrard's runners, they go up and down the pitch, they press, they harry and they tackle, quite simply because he can't. Ideally you have a player behind them to cover the space they leave behind, who has a positional sense to mop up the passes that get through and the runners who get through.
To fix the problem we're going to have to buy someone, someone like i just described, i.e a Matic, Carvalho, whoever. For what it's worth I think Henderson/Coutinho/Allen all do their midfield roles well when played there. But, for now, the 1-2 midfield isn't going to work with Gerrard there, more so against top opposition.