There's no way we aren't staffing at least five starters in addition to Bello. Even if Sale is completely healthy, he's going to have an extremely reduced workload and likely wouldn't be much counted on for the playoffs. He was already tiring down the stretch in 2018-19, and since then he's thrown a total of 49 innings.
I love moving Whitlock to the rotation, but we probably also can't count on him to handle a full starter's workload coming off a 78 IP season.
I think Bello is likely to be one of the team's best starters next year, but since we badly need to fill those innings, it makes sense to notionally consider him a #6.
Sox starters threw 807 IP last year. They threw 871 in 2018. They threw 951 in 2017. Let's aim for 850 from the 2023 crew:
Sale - 120
Hill - 120
Whitlock - 120
Bello - 150
Pivetta - 175
Total: 685
So, you'd need a 165 IP starter to make up that gap and stay away from the JAGs, which is a really healthy single-season total these days. I'd say it's unlikely that those innings come from Crawford, Paxton or Winckowski. And that assumes that Hill returning is a sure bet, which it might not be.
Here's the catch, though. Whoever that 165 IP guy is, he can't exactly bump Bello to Worcester, because you need his innings to come at the major league level. Otherwise, you're replacing more MLB innings. Bello is unlikely to throw much more than 160 IP in a completely healthy season. It's rare for a 24-year old to throw that many innings in a season -- only 32 have done it since 2017.
And then there's the playoffs, which I'd say we're likelier than not to make next year. That rotation is not well built for a playoff run even if everyone is completely healthy, should we make it that far, because of various inning restrictions.
Honestly, it makes a lot of sense to have a six-man rotation (cough, cough, Shohei?).
To start another conversation: if Bogaerts' asks are beyond what makes sense for the club, is there any chance we could pry Ha-Seong Kim from San Diego? He's not a Bogaerts-level offensive player so far (well, he was in KBO), but he looks like a plus defender who is useful on offense. The Dads should have Tatis Jr. and Cronenworth holding down the middle infield, at least until Tatis, Jr. injures himself in a freak helicopter accident or something, so they may wish to cash in on a guy on a valuable contract who is probably overqualified for a bench role.
(To be clear, Bogaerts would be my Plan A, but I wouldn't want to give him $200m.)
Kim is on a sensible $7m AAV deal through 2024, after which he still has two seasons of team control at a salary TBD by the arb process. That suits the probable Mayer timeline pretty nicely, I'd think.
On the field, he's a great defender at SS by dWAR and OAA. He's had one poor offensive season (202/.270/.352 on a .241 BABIP) and one pretty good one (.251/.325/.383 on a .290 BABIP). The contact quality matched the results each season, so I don't think the low BABIP in '21 was fluky. He also improved on K% and BB%, so I think he was just adjusting to the league. He's better against lefties, but playable against righties. Pretty good contact skills; not at all a barrel monster, but has a bit of pop; pretty fast runner. He hits a fair amount of moderate depth fly-balls to left field, so Fenway could boost both his BABIP and SLG a bit, especially coming from the cavernous and sometimes fogged in parks of the NL West.
FWIW, a ~100 OPS+ starting SS who is a 2 wins up on defense is a ~4 win player; if he were a sure thing to produce that line, he wouldn't be available at a price we'd want to pay.
Such an acquisition would make sense in a context where we were adding bigger bats in the OF and DH. Dude was a beast in KBO, so there may be some more offensive upside in there, but I think his 107 OPS+ in 2022 is probably a decent baseline going forward.
BTV thinks Houck could return him straight up, which I think is probably about right, not as a proposed package, but as a gauge of value.
Kim would be a great target if things go that way. The defense is spectacular, and he was one of the best bat-to-ball hitters in the game last year. A lot of people would howl if we replaced Bogaerts for a .250-hitting shortstop with so-so pop, but that doesn't make it a bad idea.