Making Sense of the Assets Chaim Bloom Leaves Behind in Boston — Part 2, The Pitching Staff

Kees van Hemmen
10 min readSep 27, 2023


Welcome to part 2! If you’re reading this and haven’t yet read the introduction to this series, I suggest you read that first here. Additionally, if you haven’t yet read part 1, on the Red Sox’s position players, you may want to redirect yourself there first. You can find that piece here. Otherwise, dig in. Below you’ll find an assessment of what can be expected of each of the Red Sox’s pitchers who are contracted long term to the ball club. Keep in mind the following: the easier to assess a given player is, the less airtime they’ve gotten in this piece. I’m not here to insult your intelligence by telling you good players are good; I’m here to talk about things you (hopefully) don’t know, or aren’t yet sure about. Let’s dig in.

Brayan Bello:

His strikeout rate and walk rate were both down this year, which is a bit of a mixed bag in terms of the “surface-level peripheral metrics” (do those words in that order even make sense? I think so), but his calling card groundball rate remains very high. Given that the recent addition of a sweeper seems to have given him another put away pitch to go with his freakish changeup, there’s no reason why he should be anything less than a #3 starter in this rotation going forward. His FIP and xERA sit in the mid-4s, but frankly I think that’s more a product of some weird pitch mix, location, and sequencing decisions than a true commentary on the quality of his stuff or his ability to tunnel and locate his pitches. For instance, a huge amount of his hard contact in the air this season has come off 4-seamers deliberately thrown below the belt.

If he simply stopped throwing that pitch, in that location, his advanced metrics would look very different — and I don’t imagine such a change would drastically hurt the viability of the rest of his arsenal. With another offseason of intentional refinement, I expect those numbers to improve. If he stops throwing meatball 4-seamers and leans into the swing and miss a bit more, he might even start knocking on the door of ace status. If you’re a Red Sox fan how can you not love this guy?

Verdict: Cornerstone Number 3 starter, upside for more.

Kutter Crawford:

Frankly, Crawford’s probably a little under-loved given what he’s done this season for the Red Sox. Even at surface level, 20 starts to the tune of a 4.26 ERA is solid production. You might argue that he’s basically never facing the order a third time, and when he does he’s getting crushed. That is a fair and poignant criticism, but in the face of all the other positives during his time as a starter that one negative feels rather unimportant. His FIP (4.10) and SIERRA (4.07) both support the notion that he’s been at the very least serviceable in his predominantly starting role, and an xERA of 3.62 perhaps dishonestly promises even more upside. It’s worth noting that the publicly available advanced metrics absolutely love this guy: Fangraphs’ Stuff+ grades his 4-seamer, cutter, and slider as all being significantly better than average on the basis of their velocity bands and break. The 4-seamer in particular has fantastic characteristics: where his 2.7 inches of ‘rise’ above average on the pitch places it seventh in baseball, he pairs that with 2.4 inches of ‘run’ above average — no other pitcher in baseball has more run on their fastball than that while also generating more than 1.5 inches of rise above average. It’s basically a unicorn pitch, that he also shows out of hand very late with his wonky arm action. In a team with two other young guys who were meant to prove their starting chops this season in Tanner Houck and Garrett Whitlock, Crawford has been the standout by far. The guy can start. Whether that’s the most efficient way to use him, given how dominant he and Nick Pivetta have been out of the pen in long-man roles, is another question. But the decision here is easy for me.

Verdict: Number 4/5 starter with a short leash. Long term swingman.

Garrett Whitlock:

Before this season, I was firmly in the camp of those advocating for Whitlock to give starting another try. There was no doubt he could be a dominant reliever. We had seen it. But there was also no doubt that using him as such capped his value. Why not find out if he could do more? He was a young, robust pitcher with a diverse arsenal of major league pitches and plus command. These are the things you do in (forgive me for saying) a “bridge year.”

By the same token, I admit the experiment has failed. That’s not to say that I think it’s impossible for Whitlock to ever be a starter — but, in the context of the Red Sox, who need to win next season, it would be folly to go into the year expecting him to provide you with 30+ starts of sufficient quality. What can be expected, though,, hopefully,,, I think,,,, is that he do what he did in 2021. Or at least something like it. His control hasn’t gone anywhere: he actually walks batters less frequently now than he did in 2021. His slider, which is now a sweeper, has even generated more whiffs this season (46% whiff rate) than it did in 2021 (39%). His changeup characteristics haven’t changed (when aggregated across a full season — in season they’ve actually been all over the place month-to-month) from 2021. His sinker velocity and results are down, but one would hope that’s salvageable with a full time return to the bullpen. A lights out long reliever obviously isn’t as exciting as a workhorse, middle of the rotation starter, but he can carry plenty of value as such nonetheless.

Verdict: Long relief, ideally as a weapon. Bullpen cornerstone.

Tanner Houck:

At this point, if you haven’t heard the news, you might live under a rock: Tanner Houck can’t get through an MLB batting order a third time.

He’s tried all kinds of things to give him the mix he needs to do so. For instance, he’s tried a cutter:

He’s tried a splitter:

I don’t have a third thing to add here to make this a nice set of examples, but rest assured that — despite those nice numbers — neither of these two pitches has done the trick and gotten him through the order again. His splitter has excellent characteristics, good underlying numbers, and plays with both his delivery and the rest of his mix very well. But, it’s gotten hit this year and according to baseball savant is the second worst splitter in baseball on the basis of outcomes.

The cutter has been the most effective of Tanner’s fastball varieties, but he’s dropped its usage since his injury, and its characteristics aren’t great. It barely breaks (4.6 inches below league average horizontal movement) and it’s pretty flat (1.1 inches below league average rise). This isn’t unheard of — sometimes cutters are effective because of how they play off of a pitcher’s other hard offerings, as opposed to being filthy in their own right. The weird bit is that Houck’s cutter is not helping his four seamer play up — Houck’s fastballs are getting crushed to the tune of a .431 wOBA and .385 xwOBA. Part of me wants to see him abandon the 4-seamer for the cutter entirely in an extremist’s interpretation of this Fangraphs article, but I’m far from confident that’s what gets him over the hump here. It’s been two effective additions to his arsenal, neither of which have seen his results as a pitcher improve.

All of which is to say Houck is arguably an even weirder case than Whitlock. He absolutely can /start/ games, in the strictest sense of the word. However, he can almost never finish them (translation: finish the fifth inning) without imploding and putting the win in jeopardy. This is not an issue unique to him: many pitchers fall apart the third time through the order. However, if your plan is to use him as a starter it basically means you have two guys (Houck and Crawford) who you’re almost certain to need a quality long man to pair with. That’s not an ideal scenario from a pitching staff construction standpoint, especially coming off a year wherein arguably the team’s biggest problem seemed to be constantly depleted middle relief. I think where I land on this is, given that James Paxton is out the door and a wise man would not hinge the Sox’s season on Chris Sale, is that Houck starts the season as a high end multi-inning guy out of the bullpen but stays on the short list to fill in as a starter if and when injuries strike the rotation.

Verdict: Swingman. He’s too weird to call a cornerstone, but it definitely feels dismissive to say he’s not a part of the long term future. Tradeable in the right circumstance, perhaps.

Josh Winckowski:

There’s not much to it when it comes to Winckowski. His stuff does not play as a starter. It plays just fine as a reliever. His 2.93 ERA on the season flatters to deceive (3.86 xERA, 4.03 FIP), but there’s no denying he has real value in some kind of role out of the bullpen. A new pitch mix that emphasized his cutter, along with some extra giddy-up on his sinker, have given him enough swing-and-miss to increase his strikeout rate in his new role. That, coupled with a robust 51% ground ball rate on batted balls, has allowed him to limit damage when runners have managed to reach base against him. I’d be dumbfounded if he ever returns to a starting role. I’d also be surprised if he wasn’t an important part of the bullpen for the Red Sox in the coming years. There’s very little controversy here.

Verdict: Middle/late inning reliever. More cinderblock than cornerstone.

Brennan Bernardino:

Bernardino is the bargain-bin buy by Bloom that brought back the biggest bang for his buck. I just wanted to write that sentence, but it’s also, arguably, true: the Red Sox picked up Bernardino off of waivers from the Mariners early this season, and since then he’s done nothing but provide quality innings as a lefty specialist and opener. There’s nothing mind blowing about him as a pitcher — his 3.35 ERA and 4.14 xERA are good-not-great for a lefty specialist who’s seen his fair share of righties this season.

Bernardino is basically a two pitch pitcher, throwing both a sinker and a curveball from a low arm slot. He generates a ton of ground balls and generates a healthy strikeout rate, predominantly on the strength of his breaking ball, which breaks more like a slider than a curve. He actually throws the curveball in the zone a lot, which is a bit unorthodox, but also explains how he’s managed a 26.3% K rate while only getting opposing hitters to chase pitches out of the zone 18.3% of the time (that’s in the 1st percentile league wide). Curiously, hitters just don’t swing at Bernardino’s stuff very often. It’s a really odd way to get strikeouts, and probably not entirely sustainable, but he does stay away from the heart of the plate, his curve generates enough whiffs and his sinker enough weak contact that he should be able to maintain his utility going forward. Basically, he’s a lefty specialist who costs nothing. Nice.

I’ll leave you with this on Bernardino: the pitchers in the Seattle Mariners’ minor league system have the lowest average arm slot of all minor league systems in baseball. They also throw more sliders than any other farm system in baseball. By a lot. The Red Sox minor league system also has a huge skew towards pitchers with low arm slots. Their minor leaguers also overwhelmingly throw sliders with almost no vertical break. Bernardino’s curveball is basically a slider, and as such he falls directly into the platonic ideal of Mariner-Sox pitching development. One wonders if those facts played any part in Bernardino’s acquisition this Spring. Food for thought, or perhaps just a fun fact.

Verdict: Lefty specialist of the immediate future.

Chris Murphy:

Murphy, in my view, is the player who most embodies Chaim Bloom’s vision for the Red Sox.


I don’t mean this as a diss. Bloom, throughout his tenure in Boston, lamented the organization’s lack of depth. Specifically, he focused on the absence of MLB-ready pitchers in the minor leagues — controllable guys who the Sox could bring up and down and use to get Major League outs as necessary. Not Major League innings. Major League outs.

To whatever extent Bloom’s time in Boston was a disappointment, Murphy has been a sign of success in that regard. Boston’s pitching staff at the Major League level this season fell apart over and over again, in both predictable and unpredictable ways. Murphy, despite his 4.66 ERA (Update: 5.05 ERA, zoinks Scoob), was hyper-effective through his first two months in the Major Leagues this season. He turned into a pumpkin in August, but his underlying numbers remained fairy-godmother-strong. The nerdy expected metrics like his breaking stuff on the basis of whiff rates and quality of contact, and his curveball stands out in particular as a plus pitch in terms of its characteristics. His expected ERA and FIP indicate he’s closer to a 3.75 ERA guy going forward than a 4.75 ERA guy. Multi-inning left-handed relievers? With options left? In pre-arbitration? That’s the Rays-ian stuff that Red Sox fans were sold when Bloom arrived. On the whole that was never delivered, but Murphy — whose role in the coming campaign will likely not diverge too much from his current one — has the potential to be a long-lasting birthmark (or scar, depending on your outlook) of where Bloom hoped to go with the Red Sox pitching development in coming years.

Verdict: Up-and-down guy who’s good enough to stick.

Objectively, this is a large group of young pitchers who can get MLB outs. Most teams do not have 4 guys between ages 23 and 27, in pre-arbitration, with a real chance to start Major League games. That said, the odds are that at most 2 of the players in question will ultimately achieve that feat, and given the lack of reliable veteran starters on the Red Sox payroll, that makes the picture of the pitching staff far more blurry. The good news? You’ve made it to part 3, where I finally start to tie up the loose ends in this series and begin to make sense of it all. Go ahead, don’t be shy: click the link and rejoice. Part 3 awaits.