Rangers slipped out of the Barclays Premier League after a mundane 0-0 draw at Reading last weekend, a result which also relegated the Royals.
"I don't think they have lacked desire, what they have lacked is ability," he said. "People keep saying what a good squad we are and that is absolute rubbish. We are where we are because of how good we are. It's not because they have not tried."
He added: "It's not been a lack of desire, it was a badly balanced squad that lacked the ability to stay in the Premier League. They are not a bad bunch of blokes and I find them good to work with.
"I was walking behind him (Bosingwa) after the game and I was smiling. I'd been crying all week after we got beat by Stoke and Wigan. He was walking down the tunnel and another Portuguese lad said something to him and he went laughing."
There will be no let up for Redknapp as he will welcome Arsenal to Loftus Road on Saturday evening, with Champions League qualification on the agenda for Arsene Wenger's side.
But looking towards the future, with a number of established internationals in his ranks, Redknapp can expect a busy summer of batting off phone calls from Premier League managers hoping to poach him of his star talent.
The 66-year-old has already said top money will have to be paid for the likes of Brazil goalkeeper Julio Cesar, who is reportedly a target for Arsenal.
"Well, Arsene Wenger will be here tomorrow if he's interested (in signing Cesar), I'm sure he will speak to me then," Redknapp said.
"He is a top goalkeeper so I could well understand that, but it would take a good offer. He's a good keeper. You have to get your value. He's a Brazilian keeper a great lad and he will cost money."
- Sports & Recreation
- Arsene Wenger