QPR's miserable away form continued in the Premier League as they lost for the 10th time on their travels this term.
The hosts opened the scoring with a fine solo effort from Scott Arfield before former Burnley man Charlie Austin levelled from the penalty spot.
Danny Ings scored what proved to be the winner in the 37th minute, though, when he controlled Ashley Barnes' long pass before turning Richard Dunne and Steven Caulker to slot past Rob Green.
And manager Redknapp left his side in no doubt as to his unhappiness with the quality of his team's defending.
"I thought at 1-1 they'd lost their way a bit and we were right back in the game," he said. "It was a horrendous second goal, it was a shocking goal. How we don't defend better in that situation, it cost us dearly.
"It wasn't easy but we couldn't blame the conditions for anything, defenders have to defend. The first goal we had three men around their player I mean we're not talking about Lionel Messi are we? He's gone past three players far too easily.
"The second goal was poor defending, the ball dropped between two defenders. We have to clear the ball, get the body in the way and be stronger. You can't give goals away like that and win football matches."
Redknapp also played down reports that members of his squad were involved in an angry exchange with supporters at the final whistle, with goalkeeper coach Kevin Hitchcock leading centre-back Dunne away to the tunnel.
"I think it was only Richard Dunne, someone said something to Richard," he added.
"Kevin Hitchcock went over and took Dunney away, he's a great lad and he might have got the hump. He didn't go over to have a row with anyone he started applauding, I don't know what happened."
Redknapp also explained his decision to hand Adel Taarabt his first league start of the season, having criticised the Moroccan's professionalism earlier this campaign.
"He's trained OK and I haven't got a lot of options up front," Redknapp added.
"I have Bobby Zamora and Charlie Austin. Bobby couldn't train on Friday because he had a sore back. I took a gamble and threw Adel in I thought he did okay, he worked hard."
