Sunderland boss Sam Allardyce was left fuming after his side shipped three goals in nine first-half minutes against title hopefuls Manchester City.
Defeat again left the Black Cats boss - who made six changes for the trip to the Etihad Stadium - questioning what his best team or system is.
Sunderland, missing Younes Kaboul through injury, were torn apart inside the opening 22 minutes with Raheem Sterling, Wilfried Bony and Yaya Toure all capitalising on some comical defending from the visitors.
Sterling opened the scoring after just 12 minutes - beating Billy Jones in the air - and nine minutes later they had the game wrapped up.
Allardyce, who described Kaboul's prolonged absence as a major blow, said: "Three goals in nine minutes.
"Three goals we could have done a lot better with, particularly the first and third.
"It seems to be the case for us at the moment, where the last three games we have gifted teams goals.
"And then found it very difficult to come back from.
"As much as you change the squad around, which is what I have been doing.
"You think you are going in the right direction, clearly in the last three games we are slipping back.
"It is hard work, to really think now what is the best team?
"I have looked at so many players and systems."
One of the few bright spots on an otherwise miserable Boxing Day afternoon was the return of Lee Cattermole from injury.
He came off the bench in the second half, providing a fortunate assist for Fabio Borini's second goal in the space of seven days.
Allardyce added: "It is good to have Lee Cattermole back but the big loss is Younes Kaboul.
"Until we get better defensively as a team we will struggle to get results.
"As a team, we don't defend as well as we should."