Morale plummeted under Paolo Di Canio, with the Italian's coaching methods and disappointing results on the field leaving all concerned at the Stadium of Light in a serious slump.
Something had to be done to turn the tide, and the appointment of Poyet as Di Canio's successor has the Black Cats moving in the right direction again.
There have been a few wobbles, but impressive victories over Newcastle United and Manchester City have Sunderland just three points adrift of safety.
Fletcher said in the Daily Express: "The level of confidence we displayed against City was a result of the way we performed a few days previously against Southampton.
"Football is like that. All of a sudden there is a bit of confidence and belief amongst the boys. We got the points against City and nobody can say we didn't deserve them. Hopefully it's an omen and we can keep that sort of performance going and, more importantly, that sort of run of results.
"The manager wants us to keep the ball a lot more and we know if we do that we are not going to get rolled over by other teams. We have done that a lot more in our last couple of games and we've got some decent results with those tactics.
"It's been great for myself under the new boss. I've had a few problems with injuries and he has looked after me, so I'm very grateful. He is enthusiastic and he comes in with a smile, as do his assistants.
"It's good to see that at the training ground every day and does help because it gives everyone a lift.
"We have shown we know how to pass the ball about. Look at Wes Brown at the back. He's one of the best passers of a ball I've played with. He was fantastic against City and showed what a great defender he is.
"Wes won everything there is to win at Manchester United. He has showed in just a couple of games that he is just class. He would be very important to any side, so we have to hope he can enjoy a string of games because he would make a difference to any team at any level."