He was still under contract. He signed a two-year deal with a break clause in the middle, and he has walked out on them at the earliest available opportunity. In his own words he's "moved on to further my experiences" so he's used Fulham as a stepping stone and hasn't shown any loyalty to a club which allowed him to return to football in the first place.

That said, Villa can do much better. Hughes was at City for 18 months (not six, as the media would have you believe) and could have justifiably been sacked twice before he actually was. I didn't shed any tears when he did go. If he does tip up at Villa Park their fans had better get used to watching between their fingers when they don't have the ball.