To be fair though, Vaughan's poor form was acted on and Flintoff in my view a Bowler who can bat a bit, nothing more. As for Cook and Bell, they have also had poor seasons but they supposedly have potential to improve, and to be honest I can see where they are coming from, however Collingwood is getting on, he isn't really going to improve much if we are honest. Someone like Shah, Key (obviously elsewhere in lineup), Denly, Vaughan or Rashid (moreso as an all-rounder) could score more runs and apart from in Vaughan's case, are maybe on the younger side so the potential is there. I personally wouldn't have Bell or Collingwood in the team. This is debatable, but Cook has been worked out IMO, time for him to work hard at his game during the county season.
The players I mentioned above, along with James Foster, Naps in ODI's, Morgan, Malan, Joyce etc can't be far away.