The Uruguayan struck three minutes from time after a Paul Devlin penalty cancelled out Robbie Keane's opener.
"It was, yes," said Simon of the welcome winner. "I thought it might be the same old story again. They battled hard, closed us down and it was a great finish by Gus in the end.
"Hopefully things will turn our way now."
The Welsh midfielder agreed that, after leading for 70 minutes of the game, a draw would almost have been as big a disappointment as a defeat and hopes that a turning point has now been reached.
"I think so. We had to get a win to hopefully get us on a run now, we've got the first one which we were finding difficult and now we've got to build on it.
"Hopefully it will turn on that. The lads have given it all they can, it was a hot day and we worked hard as did Birmingham.
"It took a goal like that to turn it in our favour."
Simon Davies admitted that Gus Poyet's winner provided a great sense of relief after recent setbacks.