When playing the 4231, the 2 in the middle have to be complete specialists at their respective roles, usually one enforcer, defensive minded player and one who keeps play ticking over or a box to box.
I look to Chelsea to see where this works, Matic the enforcer and Fabregas ticks it over brilliantly.
Or City with Fernando and Yaya.
In my opinion, Gerrard is neither of these and it for this reason it fails. The reason we were so successful when Gerrard was out was because Lucas is the enforcer and Henderson the box to box.
I think our midfield 3 should depend on the opposition, if we're facing a reserved defensive team which parks the bus like Villa yesterday then we need to expect we'll have a lot of possession and against such an opposition Gerrard doesn't work as well as he usually looks long.
Without a shadow of a doubt, the 442 diamond is the best as seen by us winning 7 out of 8 of our games when playing this formation. In such a case, I think Gerrard thrives hendo has to play and there can be flexibility between Allen and Can, depending on form..current form Allen is incredible and has to start.