"What went wrong actually happened before Fillory," she said. "A mistake. You know, the kind I've been making since the test."

Mistakes that were kind of Jane's fault. But then if Julia being kicked out of Brakebills is the only thing stopping them all from having been murdered by The Beast...? No, that's all just passing the buck. Jane is why she was kicked out of Brakebills but everything that happened after that was her.