Prior to his TJS, he wasn't good in MLB (he was projected to be and rushed through the minors). Since coming back, he's only pitched 140 innings of high quality ball. It's not a track record I can really trust TBH. Maybe he's a #2 or even better? I just haven't personally seen him pitch and am only going by his FanGraphs, bref and Savant pages.
I'd be more comfortable with Ryan than Bubic, but there's a very good chance that Bubic is better than Ryan. Ryan is more of a known commodity and I believe the Sox could really make a run with him and Crochet.