I have only seen her in Ferris Bueller’s Day Off, but given the staying power and popular reach of that film, I have been surprised that Mia Sara did not appear in more noteworthy roles, or at least in more noteworthy films. I don’t know if it was a question of acting chops or her own professional, and personal choices, but she had a look in that film that seemed like it would start a big career.
Edit: I’m surprised to get much response on this answer. I do appreciate the comments. Understand that I wasn’t answering WHY she didn’t have a huge career, only answering that she seemed like a star waiting to happen and then (thanks for the details!) she had a lot of work but nothing after what could/should have been a breakout role. I have no idea what the industry thought of her after FBDO and after all the revelations about how things happen in Hollywood I would rather NOT know what they thought of her prospects.
