Hawkins leaves as Riddle steps in (More on Story)
Hawkins who joined the Blades 5 months ago had the oppourtunity to go to Old Trafford and Blackwell says he didn't want to stand in his way.
Blackwell said:"Richard Hawkins got the chance to go to Manchester United and i didn't want to stand in his way."
"Dean has come into help us until the end of the season. It was nice to see him on the pitch working with the players and i think the fans appreciated his hard work and organisation at Home Park."
Riddle is an experienced fitness coach and has worked with Blackwell at both Blades and Leeds United. He as also worked in cricket and rugby league.