There Were Fewer Homers This Year, but the Long Ball Still Reigns Supreme
MLB’s plan to de-juice the baseball this year seems to have worked. Home runs were down in 2021 compared to the last couple of seasons, though not by so much as to warrant a complete shift in the game’s current offensive paradigm. Instead, run scoring — which remains heavily concentrated around home runs — decreased overall. Non-pitchers hit just .247/.321/.418 this year, representing the second-lowest batting average in the live ball era (1920-present and excluding 2020) but the fourth-highest isolated power.
In slightly de-juicing the baseball, MLB erased some home runs. But as we can see in the sudden drop in batting average, which is down nine points for non-pitchers compared to 2019, shaving off homers didn’t result in other types of hits. As I wrote in my second of two pieces analyzing early 2021 home run trends, these lost homers mostly just became outs. That explains the significant reduction in overall offense, even as the league-wide home run total remained quite high in the context of baseball history.
With the season now officially complete, it’s time to revisit some of those early trends to get a final estimation of the effect of MLB’s de-juicing. Of course, there is a significant, potentially confounding, variable that makes 2021 different from other full seasons and complicates our analysis: the midseason enforcement against the use of sticky stuff. I will try to account for that here, though it probably deserves its own standalone examination.
I’ll get to figuring out the exact effects of the 2021 ball in a moment, but first, let’s discuss the top line figures. Batters hit 5,944 home runs this season, the third-highest single-season total in baseball history, behind just 2019 (6,776) and ’17 (6,105). The Blue Jays led baseball with 262 homers, which is the seventh-highest single-season team home run total of all-time. The Pirates, meanwhile, trailed the rest of baseball with just 124 long balls, a figure that is tied for 1,250th out of the 2,985 team-seasons on our leaderboards. The four homer-happiest team seasons all came in 2019, with the Twins’ 309 home runs that year the most ever for any team in a single season; the Marlins hit the fewest home runs in 2019, with 146.
Five players hit at least 40 home runs this season, with Vladimir Guerrero Jr. and Salvador Perez tying for the major-league lead with 48 apiece; Shohei Ohtani (46), Marcus Semien (45), and Fernando Tatis Jr. (42) joined them in the elusive 40-home run club. All told, 43 players hit at least 30 home runs this season and 102 players hit at least 20. In 2019, Pete Alonso led baseball with 53 homers; ten players homered at least 40 times, 58 hit at least 30, and 129 slugged at least 20. No matter how you slice it, 2019 was a fireworks show compared to this season.
Here’s what major league home run totals have looked like since 2015. Metrics such as home run per plate appearance and home run per batted ball are especially key, as rule changes (such as seven-inning doubleheaders) and a decrease in batted ball events overall can influence the raw total:
| Season | HR | PA | BBE | HR/PA% | HR/BBE% |
|---|---|---|---|---|---|
| 2015 | 4,909 | 183,627 | 130,506 | 2.67% | 3.76% |
| 2016 | 5,610 | 184,577 | 128,856 | 3.04% | 4.35% |
| 2017 | 6,105 | 185,295 | 127,599 | 3.29% | 4.78% |
| 2018 | 5,585 | 185,139 | 126,324 | 3.02% | 4.42% |
| 2019 | 6,776 | 186,516 | 125,814 | 3.63% | 5.39% |
| 2020 | 2,304 | 66,506 | 44,007 | 3.46% | 5.24% |
| 2021 | 5,944 | 181,817 | 121,766 | 3.27% | 4.88% |
On a per-plate-appearance basis, home runs were down about 5.5% this year compared to 2020 and down about 10% compared to ’19. On a per-batted-ball basis, home runs were down about 7% from 2020 and about 9.5% from ’19. Those aren’t awful outcomes for my early-May projection of a roughly-8% decrease in home runs compared to 2019; that figure also estimated the home run total assuming hitters would receive the same number of plate appearances in 2021 as they did in ’19. On a per-plate-appearance basis, my early-May projection of a 3.35% home run rate was just 0.08 points off from the actual 2021 figure. Not too bad.
We can re-run my earlier analysis to see where home runs were lost compared to 2019. I again binned every fly ball by exit velocity and launch angle and took the home run per batted ball rate for each bin. Here is how the two seasons compare. First, 2021:
And now 2019:
To help us spot the differences, here is a comparison plot. Negative values represent a decrease from 2019 to ’21:
This is very similar to what I found from looking at just the April batted ball data. With a less aerodynamic baseball, the batted balls that would have gone over the wall in 2019 fell short. This had the greatest effect on the batted balls hit at the lowest launch angles because of reduced carry. Indeed, among all fly balls hit below 25 degrees of launch angle irrespective of exit velocity, 58% went for home runs in 2019 compared to just 47% in ’21. Hit the ball at or above 25 degrees of launch angle, and the difference in home run rate is just two percentage points. The hard-hit, low-launch-angle fly ball — those in the bottom right corner of the charts — just weren’t homers as often this year, as there simply wasn’t the carry on those balls there was in 2019. Again, this is exactly what we expected based on both what MLB indicated they were doing with the baseball and on the early returns from April.
Of course, there’s still the matter of sticky stuff. As Rob Arthur wrote at Baseball Prospectus in mid-June, sticky stuff might have a muting effect on home runs, with decreased carry on fly balls overall. This throws a huge wrench into our relatively neat data, providing a confounding variable that makes it uniquely difficult to compare 2021 to any previous year. While I did notice a slight uptick in league-wide offense in the immediate aftermath of increased enforcement, more research must be done to evaluate the complete effect. It also seems plausible that pitchers figured out a way to get around the increased enforcement, further complicating things. This creates headaches for analysis, so let’s evaluate the home run rates through June 2, since June 3 is when the news first broke that MLB planned on cracking down.
The numbers paint a similar story, but with a more extreme drop-off from 2019 to ’21. This also doesn’t account for other factors like weather, which can be variable from year-to-year, especially in segment-of-season sample sizes:
| Season | HR | PA | BBE | HR/PA% | HR/BBE% |
|---|---|---|---|---|---|
| 2015 | 1,481 | 58,801 | 41931 | 2.52% | 3.53% |
| 2016 | 1,766 | 61,031 | 42,556 | 2.89% | 4.15% |
| 2017 | 1,992 | 62,124 | 42,788 | 3.21% | 4.66% |
| 2018 | 1,962 | 66,200 | 44,975 | 2.96% | 4.36% |
| 2019 | 2,360 | 67,328 | 45,275 | 3.51% | 5.21% |
| 2021 | 1,879 | 61,412 | 40,365 | 3.06% | 4.66% |
On a per-plate-appearance basis, 2021 represented a nearly 13% drop-off in home run rate from ’19, though the per-batted-ball data only suggest a 10.5% decline. Both figures recovered after the sticky stuff enforcement went into effect, though, which does open the door for further research on the direct effects of the enforcement on the home run totals. It seems that, compared to 2019, a roughly-10% decrease in home runs on a per-batted-ball basis is a pretty fair estimation.
And just as I found in the piece I referenced earlier, almost all of the decrease in home run rate resulted in outs. On all fly balls in 2019, batters reached base roughly 30% of the time. In 2021, batters reached base on a fly ball about 27% of the time. A three-point difference might not seem like a lot, but almost 32,000 fly balls were hit this year; that’s the exchange of more than 900 hits for outs. Baseball’s league-wide batting average would jump back up pretty quickly if you reintroduced those hits.
Ultimately, a slight de-juicing of the baseball makes sense — I agree that there were just way too many home runs in 2019 — but doing so only further highlights the potential issues in baseball’s current offensive environment. In an era with more and increasingly precise shifts, better pitchers and pitches, and a still-pretty-juiced baseball, offense is going to remain concentrated in the long ball. But if there are fewer home runs, then the entire offensive output suffers, and that’s exactly what happened this season.
Devan Fink is a Contributor at FanGraphs. You can follow him on Twitter @DevanFink.
At what point does it become more valuable for a player (or a team) to try for line drives instead of home runs?
Is there an inherent value in zigging when everyone else zags?
If you’re a lefty with an average or better hit tool, plus speed, but zero power (ie. Ichiro with zero power), then work on hitting line drives to all fields. Dee Gordon-Strange did this for a while and had some offensive success, as did this year’s version of Nicky Lopez.
The irony there tho is that Ichiro actually was capable of displaying power during BP.
The lack of contact by hitters is mostly due to more pitch velocity and spin, and more breaking pitches. Considering the huge difference in value between homers and in the play line drive hits, I am not sure such a point exists (excluding players without power trying to hit homers) as every homer not hit needs to be replaced by a single and a double to match value.
you pretty much always try to hit line drives instead of 45 degree homeruns.
As long as we’re discussing aesthetics, I actually think the MLB product would be better with an even deader ball (talking 2011-13 levels of home runs), but you need to make contact easier to make to counteract that loss of production. In short, I think MLB should be aiming much more towards a .260/.330/.390 line rather than a .245/.320/.420 line. Nothing worse than games with a series of solo homers that account for all the scoring sandwiched in between 25 combined strikeouts. Just so… static. Baseball is at its best when there’s variety and there are multiple moving parts involved in most plays.
2019 was flat out cartoony baseball (the home run loses its magic when it’s common for it to happen like 4 times per game), and I genuinely find the lack of variety in lineups really disheartening. Since today you’re either a power hitter or a bad hitter, most of the nine guys in lineups are the same TTO hitter, just with varying degrees of success. I wanna see a mix of styles, gimme some slap hitters, some TTO guys, some aggressive Bo Bichette/Tim Anderson types, the more variety the better (this is why the White Sox are my favorite lineup to watch next to the Astros btw).
How you actually go about making contact easier is a different discussion. I’m partial to sharply cutting down on the number of pitchers on a roster from 14 to like, 11-12, (while also putting minimum time stay rules to reduce the MiLB-MLB churn of relievers), but I’d like to hear some ideas you folks may have.
Sounds like you have a fever, and the only cure is more Ohtani. Home runs, triples, steals, bunting for base hits, whatever you want.
I don’t think you’ll find anybody who wouldn’t prefer to see more balls in play, and fewer K/BB/HR outcomes. I am skeptical that reducing the number of pitchers on a roster would be effective, though. I think they’re eventually going to have to lower the mound as well as deaden the ball. Pitchers are just too good.
It does seem like the initial round of ball-deadening was reasonably effective, though.
The solutions that would work (lowering the mound, moving the mound back, etc) are probably too drastic for most people to want. It isn’t like players could simply make more contact. I mean they likely could to some extent, but I don’t think putting a couple more balls in play per year is going to be of benefit if you are losing some production on contact. The pitchers are just too good now.
Lowering the mound isn’t too drastic. It was done as recently as 1969 after the first Year of the Pitcher. This year, while scoring didn’t disappear as it did in 1968, lack of balls in play dominated the discussion. Personally I don’t think lowering the mound would do much to increase contact. Pitching, and the physical stature of the pitchers, has advanced so far since then that they would still throw it by all but a few. That few that can react to modern day velocity is getting fewer and fewer. As much as it strikes virtually all true baseball fans as anathema, increasing the distance from the rubber to the plate is probably the only answer. If it could be shown that this improved contact rates then the juice in the ball could be lowered and a game with more balls in play, along with the corresponding increase in great defense, more action on the base paths with steals and hit and run plays returning.
Lowering the mound in 1969 did seem to lead to a one-season bump in offense, but it was short lived as offense continued to crater post 1969, meaning 1970, ’71 and ’72, which led to the introduction of the DH (in the AL) in 1973. Hitting, however, still was depressed. I believe Nettles led the AL in HRs one year with all of 32. Reggie Jackson, who hit 47 in ’69, and over 40 in 1980, led the AL in HRs twice during the ’70s at 32 and 36. Mike Schmidt, one of the most dangerous power hitters ever, led the NL in HRs three straight seasons with less than 40, from ’74-’76, with 36, 38 and 38 totals. Historically, depressed HR totals. It wasn’t until the late ’70s that we started seeing offense and HRs tick up again. In the early to mid-70s, we saw the rise of the Charlie Lau-approach, more contact, line drive, opposite field. No surprise that George Brett hit all of 7 HRs in 1976 under Lau’s tutelage, but by the late 70s and into the 80s his HR numbers spiked up into the 20s, and even hit 30 in the mid-80s. Part of it was approach, but I suspect the ball was quite dead through the early to mid-70s. Did MLB purposely spike the ball in an effort to increase offense? Or was it accidental?
Anyway, I guess my point is I agree that lowering the mound may not be the answer. I do think we need to give players time to adapt. We’re more likely to see an increase in BA next year once players realize the easy HRs are no longer so easy, and they may alter their launch angles and hitting approaches to increase BA. Time will tell.
It’s just K/BB. Chicks (and dudes) dig the long ball. A home run is action. I think the babip stat warps some analytically forward thinkers on this. I’ve never heard anyone in my normal life complain about too many dingers.
Lower/move back the mound and robot umps will reduce K/BB (and speed up the game), keep the ball de-juiced and we won’t get video game home run totals. Do all of this gradually to reduce unintended consequences which I admit are all but certain but can be adjusted for.
Agreed. The only place I have ever heard or read someone complaining about home runs is here, on fangraphs
When it comes to aesthetics (and unintended consequences), people rarely know what they want.
If somebody said in the spring of 2015, a more lively ball with increased home runs
would result in less interesting baseball, it would have been an unpopular opinion.
I think a deader ball should be paired with a smaller strike zone to increase contact.
Smaller strike zone leads to more walks. Umps are having a hard enough time calls balls and strikes with the velo and movement pitchers are bringing these days.
A smaller strike zone doesn’t do much to lessen velocity. Hitters just can’t react in time to consistently hit 95-100 mph heat. Joey Votto said hitting used to be a chess game but now it’s a war.
2021’s HR total would likely have surpassed 2017’s if there hadn’t been so many 7 inning games –
2021 had ~3500 fewer PAs and ~5800 fewer BBEs than 2017
What do exit velocities look like in this time frame?
They need to stop moving in the walls but you won’t see this happen. I believe if you calculated the square footage lost by greedy owners/primadonna hitters over the past decade or two, you could find a home for a significant number of lost hits. Let men play in men-sized stadiums, not high-school sized fields. Can anyone explain why having large outfields (and more triples and ITP homeruns) is a negative or boring thing?
Can I get a list of these so-called primadonna hitters? I don’t remember the Union bargaining for control of the walls in any CBA, but I could be mistaken.
When Comerica debuted, and it was clear that they were a pitcher’s park, hitters complained. They moved the fences in. When CitiField opened and was an apparent pitcher’s park, hitters complained. They moved the fences in.
We can argue about whether that made the hitters prima donnas or not, or whether the fences were moved in response to the hitters’ complaints or for some other reason. But I can see where Horatio is coming from.
It might be interesting to look at where the contact was made on all the HR’s and what the pitch data for them was. I think there were more breaking balls and off-speed pitches this year than I have seen in a long time.
can we also get the homerun/flyball chart but for launch direction? oppo field ones also affected more than pull side.