I think at the moment I have grave concerns over Targett and Watkins. Both have had rotten seasons and if they don't turn their form around we will need to think about replacing them at some point over the next two windows. I'm singling these out as their standard of performances this season have been woefully short of the quality required at this level and they have both let us down substantially on the pitch.
Other than that I think we should always be in the market for better players, so if one becomes available under the right circumstances then we should be looking to improve on what we have.
The only player we have who is actually irreplaceable is Martinez, the rest are pretty much fair game.