The veteran targetman admitted Saturdays first-half performance against Chesterfield was the teams worst of the season.
A Drew Talbot double punished Cherries for their slow start and ruined their perfect home record in the process.
Eddie Howes men came to life after the break and captain Danny Hollands pulled a goal back with 15 minutes remaining but the Spireites hung on for maximum points.
And Fletcher, who almost secured a draw against his former club when he headed against the crossbar, acknowledged that Cherries could not afford to let their standards drop if they wanted to remain in the mix.
He said: We were always going to have a blip. Were not going to carry on breaking records and winning non-stop it was never going to be like that. Its about how we react weve got to put it right.
We know were as good, if not better, than most teams in this division when were on it, like we were in the second half.
When were not on it, we do what we did in the first half and become an average team. But were not an average team, were a very good team.
In the first 45 minutes, they caught us on a bit of an off day and were superb. In the second half, it was the opposite.
If we can have more performances like the second half, we will be up there at the end of the season, thats for sure. If we have more like the first half, we wont, its as simple as that.
Thats the worst weve played in the first half all season. And I think its the best weve played in the second half all season.
You cant have that if youre going to be up near the top. We havent had that before and I dont think well have that again.
Cherries dominated after the break with a vastly-improved display, but they ran out of time.
We came out in the second half and were different class, said 37-year-old Fletcher. We were as good, if not better, than they were in the first half.
If the game had gone on for another five minutes, I think we would have won never mind equalising.
Fletcher added: We dont want to beat ourselves up about it. If you beat yourself up about it, you end up being negative all week.
Well work on it, build up to Accrington and then youve just got to put it behind you.
We were brilliant in the second half so, as disappointed as we are, weve got to take the positives.
Cherries' Football Combination clash with Bristol City tomorrow - scheduled for Ashton Gate - has been switched to Dean Court (2pm kick-off).