The defeat means Leeds have won just one of their last five outings.
Bates told Yorkshire Radio: "Games that we have lost we have surrendered - we have gone off the boil a bit.
"After playing great against Manchester United and Tottenham I think some of the players have thought that the league is easy.
"We have the players who have the tenacity, the quality and fighting spirit to get out of our current problem. We need 28 points to win promotion and it is up to us to get on with it."
He added: "The boys need to knuckle down because some of them are playing for their jobs come the end of the season."