Critchley took charge of Hearts in October after Steven Naismith was dismissed following a winless start to the campaign, but has added just three victories from nine league games since.
The club do have the chance to reach the knockout stage of the Conference League on Thursday at home to Petrocub of Moldova.
However, their domestic form continues to stutter as they sit bottom of the league, one point behind St Johnstone.
Only Ross County have scored fewer league goals than Hearts this season, and again they toiled to create chances, registering an expected goals rating of just 0.88 despite playing with a man advantage for 90 minutes at Rugby Park.
“We did nowhere near enough, we played in front of them and square and around too often,” Critchley added.
“It was devoid of any ideas, it was an unacceptable performance. I’ve got so much going through my head, like I’ve been through a tumble dryer.
“We had enough attacking players on the pitch. We never played with personality, someone has to make something happen on the pitch and we didn’t.
“It was like we accepted the situation and accepted we were going to lose. I’ve said to the players that can never happen again.”
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