The Sharks have made finals in every season of Fitzgibbon's reign but Saturday's 36-12 defeat to South Sydney, leaves Cronulla outside the top eight.
Fitzgibbon described the two tries the Sharks scored in the final 15 minutes as representing a "false economy" as ill-discipline and handling errors put the Bunnies on a downhill run towards victory.
Fitzgibbon questioned his side's attitude a fortnight ago after a big loss to North Queensland in Townsville.
But the Sharks coach, who is usually a fierce defender of his players in defeat, could barely hide his contempt with their performance against the Rabbitohs.
"I'm getting a bit sick of waiting for it (the penny to drop) to be honest," Fitzgibbon said.
"I'm not going to shy away from it, either.
"It's up to us. We still believe we've got a good side, we've got a strong squad, but we're not displaying it regularly.
"The NRL is a tight competition and everyone's playing good footy and scores are fluctuating, momentum's fluctuating.
"What you do with that is up to you and at the moment we're waiting (and) not taking (our chances) and we'll do something about that."
Cronulla (4-5) have just one win in their last four matches and face fellow strugglers Canterbury in the opening game of Magic Round in Brisbane on Friday.
"The only way out for us is … just harden up, do the simple things better," Fitzgibbon said.
"Our strong performances this year have been strong, but it's been inconsistent.
"Until we learn those lessons, we've got to harden up and we'll do that.
"We have these wobbles every year and we tend to do something about it but I'm sick of waiting for it as well."
Fitzgibbon hinted that winger Ronaldo Mulitalo and centre Jesse Ramien could be cleared to return from injury against the Bulldogs.
There is concern over the availability of hooker Blayke Brailey, who was taken off the field with a category one concussion.
Brailey is set to miss the Dogs clash under NRL protocols but said he felt fine and hinted the Sharks could seek to overturn the concussion ruling.
That would clear the Sharks No. 9 to play on Friday in a game which represents his last chance to audition for the State of Origin selection.
"I feel good, I feel normal so hopefully I can play next week. I'm sure the club will look at it," Brailey said.
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