If you assume office and things get worse, that is in fact on you! I'm not saying Foxx's predecessor was good; Foxx's predecessor was Anita Alvarez, who was herself a trainwreck in the opposite direction.

A problem I see all the time in these kinds of public policy debates is that people have ideological rooting interests. That isn't going to get you anywhere in a debate about a major metro prosecutor's office. You can't project out "this person was progressive therefore they were good" and you can't do "this person is a law-and-order tough-on-crime prosecutor so they're good" either. It's a very difficult job. Notably: I think you'd have a hard time finding credible people who believe Foxx did a good job in her office.