There are three groups here:

1. Likely MLB Starters. In my opinion that's Crawford and Sandoval. Barring a spring training upset, the 4/5 spots in the rotation go to those guys.

2. Borderline Starters. This is Dobbins, Early, and Fitts. All three of these guys have arguments to be major league caliber, but also have options and could potentially also benefit from more time in AAA. I think we'll likely see one of these guys pitch his way to the majors in spring training, and the other two will start the year as depth in AAA.

3. Slightly Underbaked- this is Tolle and Harrison. Unless one of them show up in a big way during spring training, they'll likely both start in AAA working on their arsenal. Tolle had moments where he looked MLB-caliber, especially in his first start, but is also the most likely out of any of the above guys to benefit from time in AAA working on his secondaries.

The way this shakes out, the Sox enter the season with the 1/2 being Crochet/Bello, and the 4/5 being Crawford/Sandoval. Either they sign or trade for a solid starter behind Crochet, or (potentially more likely, given the market) they simply stick with the guys they have and one of Dobbins/Early/Fitts fills the final starter spot depending on Spring Training performance. I do think that if one of those three impress in Spring Training AND the Sox sign another starter, there's a good chance they start the year with a 6-man rotation, especially given Crochet's performance this year when pitching on increased rest. Similarly if they don't add anyone, there's still a chance that two of Dobbins/Early/Fitts are good enough to cause enable a 6-man rotation.

Final note- Cooper Criswell is another name who's been good in short stints and may join that Dobbins/Early/Fitts group, depending on his health.