QPR lost 4-2 at Loftus Road.
"I thought in the first half we played well," said Redknapp, who saw Jay Bothroyd and Fabio score late consolation goals.
"We gave away two diabolical goals away. Terrible, sloppy defending and suddenly you find yourself 2-0 down.
"We came back in the second half and I thought we would still go onto win the game.
"The third goal is offside, to be honest, but that is not an excuse. The fourth goal was another sloppy goal and you can't give sloppy goals way like that and win football matches.
"The first two goals gave us a mountain to climb. It was diabolical defending for both of them."