He and Riggleman are only here for their low price tags, and they would not get the same jobs with any other team. Rizzo is an overpromoted scout who comes across as a spineless, defensive middle manager who'll never rise any higher, and needs to kiss his boss's butt to keep a job he doesn't deserve.
If you fire Rizzo, there's some unqualified Rockies, or Diamondbacks, or Pirates scout who'd be hired to take his place. There might be a winning season or two for this org. in the next 10 years, but that's about the most anyone can hope for with this ownership.