Bruce has quickly realised in his short time at the Stadium of Light that one of the major reasons for Sunderlands failure to establish themselves as a top ten side in recent years has been a lack of resilience.
Chairman Niall Quinn has spoken at length about challenging his latest managerial appointment to change the situation and now the Black Cats boss has made it clear to his squad exactly what he is demanding.
Having been on top for almost an hour on Saturday at Burnley, Bruce was astonished at the way his team collapsed, with two second half goals from David Nugent condemning them to defeat.
Bruce met with his players before training yesterday morning to discuss his sides failings and has warned them what is required, otherwise they could be moved on at the earliest opportunity.
I would argue the mentality has not been right here for four years, even beyond that,
said the Sunderland manager, looking for an immediate response against Birmingham in the Carling Cup tonight.
Thats what we have to change. We have got to get a level of consistency.
Burnley was a prime example of where we are. We are either at the top of our game or right at the bottom, theres no middle ground to make sure we get results. Thats the mentality that we will have to change.
My experience of it is that you have to show resilience, steel and show a bit of backbone to get you through. I have told my players and I told them I wont accept it.
He added: Im not going to criticise anybody publicly, but we had a meeting to point out a few things which we have to improve. If it doesnt improve then they cant play at this football club. If they are not mentally capable then they simply arent good enough to be here.
Thats the challenge Im setting down for them. Weve got a small squad so people will get the chance to prove they can take the club forward, but the last half an hour against Burnley simply wasnt good enough.
Having learned all about the winning mentality during his playing days at Manchester United under Sir Alex Ferguson, Bruce will be working on trying to make sure his small squad finds a similar approach.
He may not be expecting them to win every game and challenge for the top four, but he said: You hope my players have got it, otherwise they cant play at this level. The top players stay at the top because they are able to reach a level of consistency at the very top week in and week out.
Thats why they are the big players. Underneath that we need players who have that mentality, even if they are not in the top four.
Bruce will this evening offer a number of fringe players the chance to prove they deserve to be regulars.
Defenders John Mensah and Paulo Da Silva will figure, with Bruce hoping both will soon be in the right frame of mind to play regularly at Premier League level.
Johns English is perfect. I can understand him being called the Rock. Daryl Murphy ran in to him the other day and ended on the floor. He has to prove himself for us now, Paulo too, said Bruce, who has one eye on Sundays visit of Wolves.
John has played around Europe, he has played in the Champions League, but he has not played in the Premier League. Thats a risk. But he went to Lyon for £9m last year and Ive got no doubts that he will be okay for us.
Sunderland (probable): Gordon; Bardsley, Turner, Mensah, Da Silva; Malbranque, Henderson, Cana, Reid; Jones, Campbell.