Blackwell, who employed Deane as a lone striker on numerous occasions this season, said: "Brian has been outstanding for Leeds United. I know why I signed him and he did exactly the job I needed him to do.
"A lot of people criticised my decision but his role has been absolutely vital. I needed players with experience and knowledge of the game at a time when the club had been ripped apart.
"I suppose Brian is an unsung hero and I'm sad to see him go, but we're moving into the next stage of our development."