MASTER NOTES: It's the baseball!

Ha! I thought so!

Home runs are way up, again. Discussion about why is also way up, again. But the reason seems obvious.

For some time, I’ve been telling anyone who’ll listen—right up until his patience ends or the eulogy starts, anyway—that the reason we’re seeing so many home runs is that the ball is different, and fantasy owners might need to figure out what to do about it.

The numbers provide ample evidence of the HR increase. Through June 20, MLB hitters had just over 2,700 HR in about 81,000 PA, 22 HR per 650 PA (HR/650). Last year, that number was under 20 HR/650.

Needless to say, these huge increases are affecting individual hitters, and in a big way. So far this year, 34 hitters already have more HR than they had all of last year, despite far fewer PA.

At the risk of giving the appetizer chefs at Outback new ideas, it’s a tater barrage of historical proportions. If the HRs continues at the same pace, 2017 will finish with something like 6,140 homers. That’s 500 more than last year, a 10-percent increase. The resulting rate of 1.27 HR per game would be by far the highest in MLB history.

Research Says: It’s The Ball

In response to questions about the causes of HR spike, MLB’s response has been to issue a “report” that the ball is exactly the same as before, with detailed evidence that goes something like—and I’m paraphrasing here—“It’s not the ball. Next question.” Some people have alternate explanations, such as, “maybe they’re using PEDs again,” or, “It’s been warmer this year,” or, “MLB says it’s not the ball, and MLB always tells the truth.”

But I have been much more persuaded over the years by a lot of expert scientific analysis that the ball has been the central reason for the significant power gains we’ve seen since the All-Star break in 2016. And recently, some new research has provided more evidence that the baseball is the main reason. Ben Lindbergh, who co-wrote some earlier studies with Rob Arthur of, has now written a followup study with the well-known analyst Mitchel Lichtman, a longtime sabermetrics ace and the author of The Book: Playing the Percentages in Baseball.

That study, published at The Ringer website, acknowledges that HR growth is a combination of factors, but argues very effectively that the ball is the primary factor. There are two main reasons. First, the coefficient of restitution. This sounds like something your payday lender hands you while he repos your car, but actually refers to the amount of energy the ball has when bounced off a hard surface. The CoR of major-league baseballs is up. I’m not sure about the numerical values, but apparently where it currently says “Rawlings,” it should be “Titleist.”

Second, the seams are less raised. This sounds like a small thing, and indeed seam height is measured in one-thousandths of an inch. But these thousandths of inches are much more important to seam height than they would be for, say, inseam height. The balls’ lower seams mean the batted ball encounters less air resistance in flight, which is also why there’s no stitching on Superman’s tights. The Ringer article doesn’t mention it, but it seems this phenomenon might also affect the movement on pitches, since differential air resistance is the reason pitches break. Less movement, more hard contact.

My Eyeballs Agree

I’ve also been persuaded by two of the experts I trust the most: my left eye and my right eye. Like you, I watch a lot of baseball and baseball highlights. And I’ve seen plenty of HR weirdness this year. Like Chris Carter, getting fooled by a Drew Pomeranz pitch, well off the plate away, lunging after it—and pulling a one-handed HR into the seats in left. About twenty rows deep, too, so no cheapie.

I was actually watching Marwin Gonzalez (he’s on my Tout team) in a game when he hit what I thought was a can o’ corn. So did he, slamming his bat to the ground in frustration. So we were both surprised that the ball cleared the center field fence. Marwin crossed the plate with the sheepish look of a guy who shanked a three-wood out of bounds, but the ball hit a tree and ricochet straight into the cup.

Or maybe you saw noted slugger Jarrod Dyson launching a missile 360 feet into the right-field seats. Dyson already has four HR this year in 234 PA, after amassing the less than Bondsian total of seven HR in his previous 1,365 PA!

And there are tons more examples of players hitting for way more power this year. If you’re like me, it seems like most of them were on your team last year.

I know it’s tough to assess the probability of a fly ball going out by watching it on TV. But after damn near 50 years, you get a feel for which balls look and sound like HR contact and which ones don’t. And this year, I’ve been seeing a lot of those “don’t’s” that somehow do.

But Who Benefits?

Really, the cause of the homer surge doesn’t matter in fantasy terms. I say it’s the ball, you say it’s climate change. I know a guy who’s sure it all has something do with Brexit.

What does matter in this power surge is how the extra homers are being distributed. The top HR guys, like Nelson Cruz, Edwin Encarnacion and Nolan Arenado, are not getting more HRs from the lively ball. The big gainers are coming from lower in the ranks—your Yonder Alonso/Justin Smoak/Lonnie Chisenhall types.

I quickly compared the 241 hitters who had at least 250 PA last year and at least 100 this year, to see which players are showing gains in their HR/650. I used the rate stat to find hitters whose HR gains are not connected to playing time.

The top three deciles in HR/650 last year have all lost ground on average in HR/650, while all the lower deciles have gained. The seventh decile (21-25 HR/650 last year) includes Smoak (+22), Sal Perez (+11) and Marcell Ozuna (+15). The sixth decile (22-24 HR/650) includes Morrison (+27), Colby Rasmus (+22) and Michael Conforto (+15). The fifth decile (19-21 HR/650) features gainers like Ryan Zimmerman (+27), Scott Schebler (+26) and Javier Baez (+13).

And so on down. Marwin Gonzalez is in the bottom of the fourth decile, up from 16 HR/650 last year to 40 this year. Chisenhall is in the third decile, moving from 12 HR/650 last year to 47 in 2017. And Alonso was way down in the second decile in 2016, a paltry 9 HR/650. This year, if he gets to 650 PA, he’s on pace to hit 50!

It makes sense that guys like Smoak would be the ones getting those extra HRs.The research suggests that the total distance benefit is six to 10 feet on a well-hit ball. For the big boppers, that just means their HRs go from being well out of the yard to way out. But those extra 10 feet make all the difference for a Smoak. I've had him on past teams, and if warning-track outs had been a category, I'd be up to my hips in trophies.

Now, some reports have mentioned changes in approach, such as Alonso’s well-publicized effort to change his swing plane to get more balls into the air, and on a higher arc. Smoak reportedly said he spent the offseason training to be more patient at the plate and to shorten his swing. Those adjustments probably have something to do with these players’ success. But even at that, it must help that the ball is going farther.


It’s hard to say how actionable the changed baseball is for the future. MLB could certainly require the manufacturer to return to previous standards for CoR and seam height. Or they could order that they replace baseballs with 10-pin bowling balls or sofa cushions. If so, we’d be right back where we were in 2012 or even earlier.

If not, then we should expect HR distribution to remain flat or get even flatter, with the top guys still in the high 30s or low 40s, but a whole raft more in the low- to mid-30s. That redistribution—more HRs overall but spread across more players getting them—will certainly affect the value of HRs. It might even affect that value this year, if other owners continue to believe that Cruz is far more valuable than, say, Smoak, because they think Smoak is being fluky.

In all, it's tough to say what we can do beside mind the oldest adage in sports: Keep your eye on the ball.

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  For more information about the terms used in this article, see our Glossary Primer.