The Black Cats, abysmal in the opening-day defeat at Leicester last weekend, were arguably even worse in the 3-1 loss to Alex Neil's newly promoted side with many in the crowd of 41,379 turning their anger on owner Ellis Short long before the final whistle.
Russell Martin and Steven Whittaker handed the visitors a deserved 2-0 half-time advantage and Nathan Redmond put the game beyond Sunderland's reach 12 minutes after the restart.
Substitute Duncan Watmore pulled one back late on but it was little consolation for Advocaat, who is now demanding answers from his players.
"This squad must be good enough to get a result against Norwich with five new players. There's something wrong. That's quite simple,” said the 67-year-old.
"I've an idea about it but on Sunday we will have a meeting and they can talk, and I will talk. Together we have to find out if we can find the solution. Expectation is high, we have to find the reason otherwise we have no chance."
Patrick van Aanholt endured another miserable afternoon at left-back, while Lee Cattermole was again ineffective in his defensive midfield role, offering a shaky backline little protection.
"I don't want to mention names, because it was the whole team, except for one or two players," added Advocaat.
"They are doing things that I don't expect from players at this level. I have to know why that can happen. It's really strange for me.
"You can play badly, but not knowing what to do makes it even worse.
"Two games and two defeats is not what we expected. With all respect to Norwich, we must get the result but they were the better side in everything.
"We have to discuss with the players how we go on. It was the same in pre-season and you hoped it would change but it is not changing. Myself as well, I am responsible for that, no doubt."