In an analysis like this, I tend to totally discount the negative WAR values — we could demote or get rid of those guys if there was a need to immediately improve those spots. And, of course, Sox are playing a longer game here. Shuster is probably the most key player. Hasn't been super impressive yet, but he's got a while to potentially return value. That's true of Gowens also but he's much more of a long shot. Shewmake is under control for a long time as well but it's getting harder to see how he becomes a good player. But sure, let's put him in AAA and see if he ever figures something out and/or gains 25 pounds.
Bummer has a 0.2 fWAR but also a 0.0 RA9/WAR because he once again has a worse ERA than FIP. Unlike last season, his Statcast xERA matches his ERA. Bummer is at least doing something a little different so far, cutting his walk rate in half. But his fastball velocity has dropped another mph (after a mph drop last year) and his whiff rate has dropped a lot perhaps as a consequence. So part of the evaluation concerns whether you think Bummer would have gained value if the Sox held onto him.