The 67-year-old belatedly accepted owner Ellis Short's offer of an extended stay on Wearside after securing Barclays Premier League survival on a short-term deal last season.
He has spent the months since then pleading for up to half a dozen "quality" players to strengthen a squad which has struggled in each of the last two seasons
However, he accepts the Texan businessman's reluctance to throw good money after bad following less than effective investment in recent years on players who are no longer part of the plan.
Advocaat told the Sunderland Echo: "We had a big past here and I know a little bit about the salary of players - average players, lower than average players - and that's crazy.
"People who bought those kind of players for those transfer fees and gave them those salaries didn't care about the club.
"And then I can understand our owner when he thinks, 'I spent a fortune' and now where are they playing, or not playing? I can totally understand him.
"Supporters have to understand that before you can have a new start, you have to get rid."
Short issued a robust defence of his stewardship last weekend when he revealed the club has already spent £21.5million this summer, although they have also raked in £9million from Connor Wickham's departure for Crystal Palace.
However, only Jeremain Lens and Yann M'Vila to date have met Advocaat's requirements in terms of the standard of new arrival he requires and although sporting director Lee Congerton is working tirelessly behind the scenes, time is running short.
Part of the problem is that the club is still paying off instalments on players who have either departed or have been deemed surplus to requirements.
Advocaat said: "[The frustration of supporters] has to do with the last three or four years
Take an example in Swansea: they were almost bankrupt, but they had ideas on how to set up a club.
"We have no time to do that because if you see what the other teams are spending compared with us, that is also a concern
But I know a little bit what we're paying now and what still has to be paid."
Source : PA
Source: PA