Kieran Agard was the Millers hero with a brace to take his total for the season to 20, while substitute Haris Vuckic added the third in the second minute of added time as the unbeaten run extended to 14 games.
"We played terrifically well," said Evans. "But we cannot think of the top two because most of the teams in that top group have won.
"We played well but more importantly we worked extremely hard. We dominated from start to finish and restricted a team of top-class players but we knew we had to play like that to beat this Brentford side.
"They arrived here a top-class side and they leave a top-class side. We knew the quality Mark Warburton had to choose from, they are going to get players on the ball and hurt you, so we had to work as hard as we did.
"We could possibly have doubled our score when you look at the chances we missed.
"But it's a clean-sheet, three goals and fantastic support once again."
Source PA