Steve Bruce said Hull made a huge mistake when they when they pulled out of a deal to sign Charlie Austin in 2013.
Bruce had lined up a £4.5m move for the striker, then with Burnley, following the Tigers' promotion to the Premier League.
The move appeared to be well advanced, until a medical highlighted concerns over a knee issue.
That condition had not troubled Austin before and has not surfaced since, with QPR being rewarded for stepping in to sign the player after Hull demurred.
Austin scored 20 times last season as Rangers won promotion from the Championship and has excelled in the top flight this term, netting 13 times to date.
Our loss is QPR's gain. Not only has he done as much as anyone this year but last season he scored the goals that got them into the Premier League.
Bruce welcomes Austin to the KC Stadium on Saturday as Hull face QPR in an important game for both sides' survival prospects.
"Our loss is QPR's gain. Not only has he done as much as anyone this year but last season he scored the goals that got them into the Premier League. That is what he was brought in to do.
"It is never easy to score goals. We are all looking for someone like that. He has got 13 and that is a healthy return with 13 games to go.
"We'd identified him. I think he would have been a real terrific player for us, as he has proved. He is a goalscorer with a fantastic attitude."
That Austin has not suffered any significant knee problems since Hull passed on him resonates with Bruce, who had a similar problem before joining Manchester United only for Sir Alex Ferguson to sign him anyway to great success.
"Going back 30 years, I failed my medical with a knee injury I didn't know I had, at Manchester United.
"They signed me on my playing record and the belief that I'd never had a bad knee.
"It went back to something when I was a kid, at the age of 12. Incredible. The sad thing (for Austin) is he probably never knew he had a funny knee, or something wrong with his knee."