I think that both the cheers that this team was going to coast to the postseason in June and the current doom and gloom are overstated.
The way I see it, there have been three phases to this season. I'm not cherrypicking these dates, so I'm sure a starker contrast could be drawn if the dates were chosen more intentionally.
- Through the end of May, the team had scored 269 runs and allowed 224 and went 32-21 (pythag: 30.9-22.1, or +.0208 per game)
- Between the end of May and the ASG, the team scored 195 runs and allowed 183 and went 23-15 (pythag: 20.1-17.9, or +.0763 per game)
- From the ASG until now, the team scored 79 runs and allowed 102 runs and went 10-12 (pythag: 8.5-13.5, or +.0682 per game)
I've been watching Fangraph's BaseRuns pretty closely throughout the season, and my recollection is that during the first phase of the season the Sox weren't really outperforming their pythag in a substantial way. IIRC there were times when they were a game or two up, but nothing alarming.
The overperformance largely occurred during the second third, where the Sox put up a really nice record against stiff competition despite having a relatively flat run differential. The overperformance continued in late July, but in the last two weeks or so the team has really cratered and the overall overperformance in this third stretch isn't quite as extreme. For example, since July 28th the sox are 3-10 while their pythag has them at 2.67-10.33, or +.0254 per game played, similar to the first third of the year.
One can make two basic arguments that this team is going to fail: that the team has been far outperforming its pythag and is due for a hard regression (which is starting to play out), or that the team's true talent level is well below that of what we've seen over the course of the season in aggregate and thus is due for a hard regression.
So that begs the question as posed in the thread title: which portion of the season is the "real" Red Sox?
Through the end of May, the Sox were playing at a level that could compete with any team in baseball. Since then, they've played like an 80-ish win team.
Let's look at some more numbers, starting with the hitting by wOBA:
- Vaz: .287 (pre-June)/.284(June to present)
- Plawecki: .305/.383
- Santana: SS/.219
- Dalbec: .279/.286
- Kike: .299/.362
- Arroyo: .309/.373
- Gonzalez: .259/.253
- X: .398/.348
- Devers: .391/.381
- Verdugo: .346/.322
- Renfroe: .320/.327
- Franchy: .222/.267
- JD: .415/.338
- Duran: -/.244
JD, Devers and X carried the team in April and May, supported by Verdugo and Renfroe. Since then, Devers has kept it up but X and especially JD have cratered (particularly since the ASG). Meanwhile Arroyo, Kike and (strangely) Plawecki have really stepped it up. Unfortunately Arroyo got injured, so the improvements from Plawecki and especially Kike haven't been enough to offset the decline of X and JD.
Franchy, Gonzalez, Dalbec, Santana, Vaz, and now Duran have continued to be awful.
If X and JD can play to their season averages going forward, this team could look really scary on offense. If JD plays more to his career norms (which could easily fall in the .380-.420 wOBA range) and you factor in Schwarber then I think the lineup is competitive with anyone else out there. It's far from guaranteed, but there are
plenty of ways that this offense could get back to doing what it did in April and May.
Let's look at the pitching staff:
- Starters in April/May: 3.37 FIP, 4.2 ERA
- Starters since June 1: 4.5 FIP, 5.07 ERA
- Relievers in April/May: 3.61 FIP, 3.73 ERA
- Relievers since June 1: 4.13 FIP, 3.8 ERA
The variation in the bullpen is pretty mild. Cora has been using the worst relievers a lot more recently to give the top performers some relative recuperation, and that's going to show up in the numbers. But I don't think we'll be seeing much of them in the playoffs if the team gets there.
The starters have undeniably been much worse.
- Eovaldi: 2.36 FIP, 3.64 xFIP, 4.01 ERA | 3.14 FIP, 3.73 xFIP, 4.13 ERA
- Rodriguez: 3.74 FIP, 3.41 xFIP, 5.64 ERA | 3.02 FIP, 3.19 xFIP, 5.02 ERA
- Pivetta: 3.45 FIP, 4.43 xFIP, 3.86 ERA | 4.81 FIP, 4.33 xFIP, 4.73 ERA
- Perez: 3.66 FIP, 4.28 xFIP, 3.55 ERA | HORRIBLE
- Richards: 3.89 FIP, 4.57 xFIP, 3.83 ERA | HORRIBLE
If you want to make a case for why the team was overperforming in April and May, I think here is where you will find your best argument. Pivetta, Perez and Richards were all pitching WAY ahead of their xFIPs. Unless there was some special sauce that was helping this trio suppress home runs, it was inevitable that the wheels would come off the bus. The sticky stuff crackdown seems to have exacerbated that further for Richards and perhaps for Perez. Both of them have absolutely fallen off a cliff and are just not major league caliber pitchers at the moment.
Pivetta is a middle case. His performance has tanked, but his xFIP is actually a hair better than it was in April/May. He's not going back to that 3.86 ERA, but he could be a serviceable 5th starter.
Eovaldi has tailed off a bit in his FIP but his xFIP and ERA are right around where they were. He just had a putrid start against an incredible offensive team. Not sure that it's worth extrapolating anything from that.
E-Rod is a very weird case. His peripherals have been great all year but his BABIP luck has been awful and thus he is one of the biggest ERA underperformers in baseball this year. Since June 1 his peripherals have actually gotten better, and his ERA has improved but not by as much as one would hope. He is a decent bet to improve over the course of the rest of the season.
The good news is that we have Houck and Sale coming in to take over for Perez and Richards. Will the rotation as a whole perform like it did in April/May? Probably not. But it could be close, and there's a reasonable scenario where the rotation ends up in a better place from a playoffs perspective. If Rodriguez fixes whatever his problem is (or just gets lucky), Eovaldi keeps doing what he is doing, and Sale/Houck hit their potentials it could be a very competitive rotation.
TL;DR: The Sox are not looking great now, but those who are saying that the team's current performance is reflective of a regression that was inevitably coming all season wrong are overstating their case. The team was legitimately performing at a very high level through the end of May, and recapturing that level is absolutely plausible. If X and JD start hitting again (plus/minus Schwarber and/or Arroyo) and the second half performers like Kike keep doing their thing, then the offense in the last month and a half could actually be better than it was in April and May. The pitching staff as a whole is probably not going to return to April/May levels, but if Sale and Houck can do their thing we might have a more top heavy staff that is better suited for the playoffs than what we had in April and May. If the Red Sox play at an April/May level they have a real shot at the division and a very good chance at a wild card even if they don't overperform their pythag.