David Healy's 74th-minute header secured Leeds their first win in nine games but the real boost for Leeds was the second-half appearance of former England winger Stone.
Blackwell said: "He came on and straight away he showed the quality he's got. Stoney is nowhere near as fit as he needs to be but he's intelligent and he gets round the pitch so well.
"It's a good time for him to be showing us he can perform with the play-offs coming up.
"Stoney has worked his socks off in the gym and comes in every morning to the gym at nine o'clock in the morning and stays until six to seven o'clock at night.
"The biggest factor about Stoney is his professionalism and desire to get fit because it has been a career-threatening injury and many people would have called it quits after the career he's had.
"But his desire is so infectious that his introduction did give the lads a lift."