Sam Allardyce has held talks with Sunderland's players this week after being left "baffled" by their collapse at Everton.
Allardyce lost a Premier League game by a four-goal margin for the first time since January 2013 in Sunderland's Goodison Park drubbing last weekend, with the Black Cats boss clearly still smarting at that result at his pre-match press conference today.
When he was appointed at the Stadium of Light a month ago, Allardyce immediately put an emphasis on defending and saw clear signs of improvement when Sunderland shipped a solitary goal in his first two games in charge.
But after watching Sunderland concede three times in seven minutes at Everton - after they had clawed back a two-goal deficit to level proceedings at 2-2 - Allardyce has tried to get to the bottom of the problem with his players.
"First and foremost, it's the responsibility of a player to continue to play his best consistently," said Allardyce.
"That's the ultimate problem the team has had this season.
"I thought I'd started to guide the players into how and where we needed to go in terms of not conceding goals.
"But we lost all that last week in the last 30 minutes, which was hugely disappointing for me when you saw the level of performance up to then.
"That has really baffled me this week, in terms of why and how the players allowed a very good position to slip away from them.
"I've talked to the players about it.
"Systems mean nothing until you play your best on a regular basis.
"The system is to suit the players' strengths and abilities, but if they don't reach those on a consistent basis, then it doesn't mean anything in helping you to win a game."