To be up to par means to be as good as what was expected, so in this context the person's accomplishments were not meeting the expectations.
Consider the statement "Once when I looked around and thought that my accomplishments were not as good as what was expected, I considered going to medical school.". Based on this "Once when I looked around and I thought that my accomplishments weren't up to par, I considered going to medical school." a true statement? Yes, no, or I don't know?