The home side, now without a win at One Call Stadium in 10 games, made a promising start and had three great chances before Hayes opened his account.
But the visitors rarely looked in danger after that as they made it seven wins and two draws in this nine-game purple patch.
Wilcox said: "We knew what Mansfield were all about and what we were going to get - they are very good at it and very hard to play against.
"They are very organised, very disciplined and we knew the ball was going to come into our box and we had to defend the second and third balls.
"We didn't do that for the first 10 minutes and we perhaps scored against the run of play.
"What a wonderful goal that was to score on your third debut for the club. To be fair to Paul that is what he can do. That's how good he is technically.
"His second was more of a striker's goal - more of a sniffer's goal, being in the six yard box and picking up the bits.
"Mansfield created a couple of half chances. But I thought we dominated and created opportunities to go on and score more goals.
"We had to make sure we made it a football match when we had the ball. If we had tried to play back to front and mix it up with them we would probably have got beaten.
"It was just about being solid and resolute and then being creative when we had the ball."