The midfielder lasted the full 90 minutes of the Black Cats' 6-1 humiliation at Villa Park, and cannot explain the performance that led to Di Canio venting his feelings in the dressing room afterwards.
"The manager was angry. This is normal - we lost 6-1," said N'Diaye.
"He said that we need to work more. We need to work more this week to beat Stoke, and he said that to us.
"It is not normal to lose by five goals, it is not normal to lose six goals in one game.
"It was a bad day. It was a very bad day for us, and I do not know why."
Two straight wins prior to the Villa defeat had raised hopes that Sunderland would avoid a late-season battle against the drop that the Frenchman accepts his side are now mired in once again.
"You can't concede six goals in one game, it is just not normal. We are back in the relegation fight."
The Wearsiders will also have to do without midfielder Stephane Sessegnon, suspended for the final three games of the season following the straight red card he received at Villa Park on Monday.
"We have other players who can step in for him and make chances and score goals though - it is up to us to start to do that if Stephane can't play," N'Diaye added.
"We have to show that we don't rely on him. It is bad for us - but we have no choice we must keep on playing."