Speaking to the Grimsby Telegraph after the game, Slade spoke of his pleasure in the victory and of the performance.
"I am delighted for the players as they put in so much effort to get such a good result against good opposition," he said.
"It was the first time we have got ourselves in front this season and that gave them some confidence. Our passing and movement going forward was a joy to watch and I was very pleased with some phases of play."
Wigan boss Paul Jewell had no arguments about the results and conceded that the best team won on the night.
"I expected to do far better than we did," he said. "Grimsby deserved to win but I am disappointed with the performance and the fact we are out of the Cup.