I was using the presumption that A) Liverpool value Carroll at over 13m, based on the fact they turned down an offer from Newcastle widely believed to be around that region & B) Demba Ba has a release clause believed to be around 7m, note I use the word presumption, I do not know if any such clause exists, but i think it was Harry Redknapp who first spoke of this (I think), in which case any potential deal involving Demba Ba would be plus cash, i´d assume.
Ba's release clause expired 31 July, so it would be difficult to move him now. I think you need to keep hold of Carroll because he is not just a threat in the air. He scored most of his goals at Newcastle with his left foot. Plus, with him in the game, he draws one or two defenders which can open up the field for someone like Suarez.
I don't think you need to change much to finish in the top six. Top four might be a tough ask this season though.

