Fantasy forecasting implications of MLB deadening the baseball

As if fantasy managers didn't have enough noise and nonsense to deal with heading into the 2021 season, we learned last week that Major League Baseball is deadening the ball. Just when we'd all adjusted to historic home run rates and the juiciness of the post-2018 baseball, they decided to de-juice.

According to reporting by The Athletic's Eno Sarris and Ken Rosenthal, humidors will be used for storage by five additional teams in the season ahead, while Rawlings has made alterations to the ball itself. For specific details — including coefficients of restitution and drag and seam tension and weights and other goodies — you should really read their story. Sarris and Rosenthal's reporting relies in part on an internal MLB memo sent to front office personnel.

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The fantasy implications of these changes aren't immediately clear, but we shouldn't assume everyone will be impacted equally. Things are never that simple. We can't reasonably expect the power landscape to look as it did in 2019, a year that produced the four highest single-season team home run totals in history (and 10 of the top 20), but we don't know the extent of the deadening.

The Athletic's report offers this detail: "The MLB memo includes a footnote that says an independent lab found that fly balls that went over 375 feet lost one to two feet of batted ball distance with the new ball." So there's that. It doesn't sound like much, but, as the authors note, an additional foot of flyball distance increases the likelihood of a home run by something like 3 percent. Sarris and Rosenthal quoted an analyst who suggested we might see a power dip of perhaps 5 percent.

Spring training will begin to answer our questions about the newly de-juiced balls, of course, but exhibition games aren't played under regular season conditions with exclusively MLB-level talent. And some of us have our first fantasy drafts coming soon, before spring stats can tell us anything at all. We're looking for any sort of edge we can get.

With these facts in mind, we decided to consult with three of the game's most accurate and thoughtful forecasters to see how they were approaching the challenge of un-enhanced baseballs. Because this felt like a problem requiring serious math-wielding professionals, we lobbed questions at the following analysts:

- Ariel Cohen, FanGraphs writer and producer of the ATC projections;

- Derek Carty, creator of THE BAT and THE BAT X;

- Harry Pavlidis, director at Baseball Prospectus, producers of PECOTA.

They were kind enough to discuss their initial reactions to a pair of questions that don't have easy answers...

Based on what's been reported so far, how dramatic a decrease in homers and run production are you forecasting league-wide, assuming you expect some decline?

Carty: "I haven't adjusted THE BAT's projections for this yet, but will be doing so soon. Based on the information we have, it sounds like we should expect about a 5 percent decrease league-wide in home runs. That's not to say we know for sure that will happen, but it's more to go on than we've ever had in the past. Most years, projecting league average is just throwing darts; we really have no idea what will happen. I know there may be some who are a little skeptical of what precisely will happen, but information like this is better than what we normally have and I trust will get us closer than any alternative, so I will be taking it at face value and relying on it. This would put the league-wide home run rate between the weather-adjusted 2017 and 2020 environments."

Cohen: "It is hard to say, since we will not have many details yet of the new ball, and, more importantly, we have imprecise information on exactly which balls were used in 2020. We will know a more exact figure fairly quickly into 2021. ... As to the decrease that I will personally project, since ATC relies on other projection models, it will take the ATC projections a few weeks to fully update and to see the full effect of the decrease on projections. I’ll guesstimate that the figure will be close to a 5 percent decrease on projected home runs."

Pavlidis: "We were already projecting to something less than the recent hot ball but we haven't made any adjustments based on the news. ... We don't even have the DH situation updated in our systems — we've been hedging that they bring it back for the N.L. this year, but we're going to have to bite the bullet and adjust accordingly. So we're already looking at a possible update over the next few weeks. If we think there's an adjustment that can be made based on the information we have about the ball, we'll do that. For a projection system it's probably going to create more noise than benefit when the ball varies a lot anyway (year to year and ball to ball) and we still don't know exactly how it's going to perform."

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Do you expect changes to the ball to impact all hitters and pitchers equally? Or are certain player types more likely to benefit or suffer?

Pavlidis: "In terms of how PECOTA works, yes. It's just a general dampening of the run environment we set things to. But there are surely going to be players impacted differently by this. Really, that's no different than any year there is a ball change, whether we know about it or not."

Cohen: "The ball will have little effect on players that tend to hit no-doubter home runs, but a noticeable effect on players who hit more just-enough HRs. One thing to note — to get a sense of the players most affected — average flyball distance will be more correlated to the potential decrease in home runs than a player’s average HR distance. Those players with low average flyball distances could be affected by as much as 20 percent.

"For pitchers, naturally, you will see flyball-leaning pitchers more affected than those with a greater ground-ball tilt. In the National League, I would expect pitchers to be more affected by the lack of a universal DH in 2021 than the change in balls."

ANAHEIM, CA - SEPTEMBER 15: Mike Trout #27 of the Los Angeles Angels at bat against the Arizona Diamondbacks at Angel Stadium of Anaheim on September 15, 2020 in Anaheim, California. (Photo by John McCoy/Getty Images)
Players who tend to hit no-doubt home runs shouldn't be as impacted by the change in ball. (Photo by John McCoy/Getty Images)

Carty: "It's unlikely to impact everyone equally, but it's also not necessarily easy to figure out who it will disproportionately impact, especially for hitters. For pitchers, low-strikeout and high-flyball guys will likely benefit the most. If you're striking a bunch of batters out and allowing fewer balls in play, it doesn't matter as much if flyball distances are diminished since, obviously, you're not allowing as many flyballs. Now, that's not to say you should run out and grab every crappy pitch-to-contact flyball guy you can find — these are generally still the worst type of pitcher — but they will receive a relative boost to other pitchers. It won't be massive, and it will be captured in the projections, so don't overreact here.

"There is also the possibility that the ball impacts more than just home runs. These things don't happen in a vacuum. If the ball is different, it won't just impact struck-ball trajectory, but also pitched-ball trajectory. If the drag coefficient increases — that is, there are more forces acting against a ball in the air — movement could diminish a bit and reduce strikeouts for pitchers who rely more on movement. This is really getting into the weeds, though, and just speculation.

"Some may wonder if BABIP will drop alongside home runs. I would guess if it does, it would only do so minimally. We know that exit velocity has a very weak correlation to BABIP — despite what many believe and what conventional wisdom may tell us — so a change like this may not make much difference. It's worth noting there's been very little difference in adjusted BABIP over the past several years despite drastic changes in home run rates.

"As far as hitters go, in theory the guys who blast their homers well beyond the fences may not be impacted as much, and the guys who struggle to reach the fences won't either. The ones that live along the fence line are likely to be impacted most. I'm not sure just how extreme these differences will wind up being, but Connor Kurcon has done some good work identifying these types of guys. Applying this to projections is not as straight-forward as most would assume, especially with the need to account for sample size and variance, but it is on my list to look into and try to incorporate."


So what are the takeaways here?

OK, that's a lot to process, and these guys are all much too smart and experienced to claim they know exactly how an altered baseball (which hasn't yet been used in a competitive environment) will play in 2021. But there are a few key things to keep in mind for those of us preparing to draft a team, or simply rank the player pool:

- Nobody doubts we'll see a dip in power from unprecedented recent levels. That's the goal, after all. An overall decrease of perhaps 5 percent in homers seems believable. If the year ahead looks like, say, the 2017 season, we're still going to see significant power totals. That year, an average MLB team hit 204 homers, slugged .426 and scored 753 runs. Two players reached the 50-homer plateau and three others topped 40. That'll do.

- Batters who routinely hit zero-doubt moonshots would seem least likely to nosedive in the power categories in 2021. Those who specialize in wall-scrapers or have relatively low average flyball distance could be impacted more severely. (Maybe you didn't need an expert to tell you this, but confirmation isn't a bad thing.) If you want to sort the tape-measure mashers from the guys with first-row power, Statcast has you covered.

- If batted-ball trajectory is changing, it's reasonable to expect that pitched-ball trajectory would be impacted to some extent as well. This could get messy — unintended consequences and whatnot. Pitchers who rely heavily on movement might be at some unknowable disadvantage.

- The reported changes to the ball seem like a pretty clear win for flyball pitchers — particularly those in the N.L., who also appear to have dodged the universal DH. Again, maybe you didn't need an expert for this one, but it's nice when they agree with the rest of us.

We're gonna have a few early reviews of the new balls soon, because pitchers and catchers report this week. Actual spring stats aren't far away. Players who've exit-velocity'd their way to the big leagues aren't about to become contact hitters overnight, so don't expect any immediate stylistic changes. If league-wide power recedes to something respectable yet less cartoonish than 2019 levels, your fantasy life shouldn't suffer.