Cooper revealed he had stern words with his players after a 2-1 defeat at Preston two weeks ago and was delighted with the response.
"I think this has been coming," he said. "We put something in place a couple of weeks ago with this game in mind and the players have carried it out fantastically well. I thought they were outstanding.
"We put another defender on and we asked one of our full-backs to stay at home rather than both going forward at the same time, we did it and still created numerous chances,
"We sustained a little bit of pressure early on which is what you expect when you come to Rotherham. and once we had withstood that some of our football was outstanding, We questioned our players after the Preston game and we have bounced back on gone on another little run.
"They deserve that's coming their way and they get a little bit of time to themselves now before we play again on Friday."
Seconds before half-time Swindon doubled their lead when Massimo Luongo's persistence paid off and he cracked a shot that hit Frecklington and looped over the keeper.
Pritchard clipped in a low ball for Nicky Ajose to slot in the third after 65 minutes and in added time sub Dany N'Guessan broke into the box and slid home the fourth.
"Pritchard's goal was a piece of individual skill and we know that's something he has got in the locker," added Cooper.
"It was something like we expect from him and he showed what he's about. He was really really good as were the rest of the team."
- Sports & Recreation