I think the Giants should sign free agent right-hander Jack Flaherty to a short-term deal. (I'll take almost anyone on a short-term deal.) He's going to give you 25-30 starts with above-average results. Flaherty's market is depressed and he needs to prove himself with a good year and then opt-out. Think Kevin Gausman and Carlos Rodon. (He's not as good as those guys, but that's okay.) It's never bad to have a surplus of starting pitchers.
Right now the Giants are expecting the kind of performance I described for Flaherty from four guys: Ray, Verlander, Hicks, and Harrison.