The former Rangers manager has admitted the Loftus Road club did not attract enough top-flight quality after winning promotion from the Sky Bet Championship.
Redknapp quit QPR in February claiming knee surgery prohibited him from seeing out the campaign, and the club's demotion was confirmed in Sunday's 6-0 drubbing at Manchester City.
Former Tottenham boss Redknapp has since held up his hands to concede last summer's recruitment sowed the relegation seed, with new boss Chris Ramsey unable to turn the tide.
"Nine of the team that started yesterday played in the Championship last year when we got up in the play-offs," Redknapp told Talk Sport.
"We finished 20 points behind (champions) Leicester and almost the same behind (runners-up) Burnley and nine of those lads are still playing.
"Eleven of the 25 in the squad that was there when I arrived were part of the team which went down two years ago.
"It has been difficult
We spent good money on three players
Two of them played yesterday, only Sandro didn't.
"The thing they have got in their favour is they have a fantastic chairman, a good board, and they have got good supporters as well, who are very loyal to the club.
"But you have to be realistic
Nine of the eleven were playing in the Championship last year and, at the end of the day, we fell short
We weren't good enough."
Source : PA
Source: PA