Dunne is too slow (hence his magnificent total of red cards) & will eventually get found out at Villa, Richards makes too many mistakes & relies on his pace to get out of trouble - still young so may yet learn the art of defending. Given is a great keeper and has bailed out his defence for both Newcastle & Man City on many occasions. Lescott & Toure have yet to convince but may gel in time.
As far as Hughes is concerned I don't think he was the right man for the job to begin with but should have been given at least until March/April to prove he was.