"She's trying really hard, but she's completely out of her element," a source tells PEOPLE of Barton, 30, who struggled to keep back tears after a poorly received performance on Monday's episode.
Before DWTS, the source says Barton "didn't really have any sort of deep desire to learn to dance, and she hadn't really watched the show before she was cast," making her journey on the show all the more challenging.
Another insider acknowledges that Barton's temperament might not be a great fit for the demanding competition.
"Mischa has never really been high-energy," says the insider. "She's introverted and quiet. She's very much like her O.C. character. She could be having the best time, but her demeanor doesn't really change."
Blogging exclusively for PEOPLE this week, Barton admitted that her debut performance on the show was "a worst-case scenario" and that weathering the critiques of both the judges and partner Artem Chigvintsev has been a work in progress.
"I respond well to criticism, but there is a balance between criticism and support that we are still working to find," she wrote.
"I know I'm never going to be a professional ballroom dancer," she added. "So for me, this experience is about having as much fun as possible."