Lucas, Gerrard, Aquilani, Henderson, Adam, Shelvey, Suso, Spearing,
Those are our current central midfield options.
In my opinion, Spearing and Adam aren't good enough and need to be shipped out.
Take them out, and we're left with Lucas, Gerrard, Aquilani, Henderson, Shelvey, and Suso. A very promising bunch of players.
Gerrard isn't going to last much longer, so bringing in Allen would be great. As a group of central midfielders at the club, where three will play at a time ..
Allen, Lucas, Gerrard, Aquilani, Henderson, Shelvey, and Suso
... would please me. None of those players are players I'd look at and feel that they're not good enough.
We'd probably need a DM to cover Lucas though. Maybe someone from the reserves/academy, just not Spearing, please.
Taking Aquilani out of there would make a big difference, for the worse.