Ii was reasonable to expect Franco to improve, he shows flashes, like the first six weeks or so, when he seems to get it, has good power, good swing, plus arm, he should be a .750+ OPS average fielding 3B. Something missing upstairs.
Herrera was a top young star two years ago, and has just spiraled down since, there's no way to predict that.
Williams on the other hand, never showed the plate discipline to have a future given his atrocious fielding.