The Pirates boss saw his team take an early lead through Alex Henshall's goal but Stanley turned the game on its head with efforts from James Gray and Kal Naismith to record their first Sky Bet League Two win of the campaign - at the 13th time of asking.
"It's a massive disappointment in terms of the result," said Ward after the 2-1 defeat extended Rovers' winless league run to eight matches.
"We started really well in the first 10 minutes, it was very positive and we got the goal which had some fortune attached to it but we had two or three other chances and could have scored a proper goal.
"Maybe we've got a little bit carried away with that and thought that everything was going to turn out okay for us and we've mislaid ourselves for the next 75 minutes."
The visitors failed to respond to the challenge in the second 45 minutes and save for Eliot Richards hitting the frame of the goal failed to really test Bettinelli as they looked to get back into the game.
"We didn't create enough chances in the second half," continued Ward. "We've tried to change the frontline but the closest we came was when Eliot clipped the top of the bar. We've tried to be positive from the start so I don't think anyone can criticise the positive outlook from the team."