The ‘deep dive' into juiced balls didn't dive deep enough

Darren Yamashita-USA TODAY Sports

Was anybody else unsatisfied with Major League Baseball's second "in-depth" look at why baseballs are flying over fences at record rates? Did anybody else think the "preliminary findings" from a panel full of some Very Smart People seemed awfully simplistic and maddeningly incomplete?

It's almost as if MLB put the panel together to give Rawlings the opportunity to say this:

"We have never been asked to "juice" or "de-juice" a baseball. And we've never done anything of the sort. Never would." -Rawlings President/CEO Michael Zlaket.

If I'm reading this right, after all this work, the panel concluded lower seams account for about one-third of the reduced drag they measured, they don't know about the other two-thirds, but that's only 60% of the equation. The other 40% of the increase in home runs can be attributed to some nebulous gray area they just labeled "launch conditions." When asked how long it would take to figure out the other 65% of the reason for reduced drag, one of the panelists got a laugh when he said "we have no idea."

This is embarrassing. There has been a ton of great research and writing on this topic ever since the home run surge began in 2016, including scientific research on the ball itself. And if there's one thing we've learned, it's that many different small changes in the makeup of the baseball can - collectively - add up to large changes in how far a batted ball flies.

There doesn't have to be any grand conspiracy at work here. But isn't it reasonable to assume that when you get cork from Portugal, rubber from Indonesia, yarn from Massachusetts, have a "special sauce" with secret ingredients that you add to the rubber during the melting process, and use an outdated, century-old manufacturing processes for "the pill" that there might be variations in the physical properties of each element of the ball from year to year? And that MLB and Rawlings have some feel by now how changes in one ingredient - or minor changes in how a ball is constructed - might impact how a ball performs? If they don't, they should.

Given all the talk about the exterior of the ball, it certainly doesn't seem like the Panel of Very Smart People was given full access to all the information they might need to deconstruct the interior of the ball, where all the action is.

And getting to the bottom of this is important. Not just for the aesthetics of watching a game. I don't get the sense fans hate seeing all the home runs fly. For all the complaints about how the game has become a game of three true outcomes, I still enjoying watching baseball every day. This is about bringing equilibrium back to the batter-pitcher matchup.

Yes, I know pitchers are striking out more hitters than they ever have. But pitchers aren't getting more swings and misses because they're working with a ball that suddenly dances more, spins more or moves differently than before. If anything, they've been at a disadvantage with lower seams. The batters they're throwing to, on the other hand, clearly have an advantage when they put the ball in play compared to a few years ago. A pitcher who is used to pitching a certain way - knowing he's made a pitch that should result in a routine fly ball out - should still be able to pitch that way, and be rewarded for making that pitch. Whenever I ask a pitcher who's been in the league for, say, at least five years whether he's given up home runs that he knows used to be routine fly balls, I've never had one say "no."

So what's missing from this discussion? A historical look at fly ball rates - and what percentage of those fly balls turn into home runs. A closer examination of the makeup of the baseball and ideas for how to make it perform more consistently. And external factors like how ballparks play and how weather conditions have a major impact on how a ball flies. With that, let's take a look at some of the explanations for the home run surge, and why there doesn't seem to be a perfect answer among them.

It's "launch conditions." Oh. My. Goodness. This is all we've been hearing about for the last four years - the Launch Angle Revolution. And now we're trying to assign a number to it - the percentage of the home run increase that can be attributed to a change in approach by hitters. Thanks to the panel, we now know that number is....40%.

So that would suggest we've seen a sharp rise - say, 40% or so - in the number of balls hit in the air over the last four years. Thanks to sites like FanGraphs, you can look these things up. From the last five years:






Line Drive Rate






Fly Ball Rates






GB Rates






So there has been an increase in the percentage of balls (LD + FB) hit in the air over the last five years.

Of 4.4%.

Line drive rates the last two years are comparable to the line drive rate in 2013, and below where they were in 2003, the second year FanGraphs began tracking batting ball data. Fly ball rates have flattened out the last three seasons at right around 35.5%. More importantly, fly ball rates are virtually unchanged over the last 18 seasons. Year to year fluctuations have been in a tight range between 33.8% and 37.9%. We saw far more fly balls in 2007, 2009 and 2010 (the only three seasons above 37%) than in 2019. The lowest rate for fly balls was in 2015 - 33.8% - the only year below 34%.

We can conclude line drive rates and fly ball rates are basically unchanged. But what percentage of those fly balls are actually now going over the fence?


















While fly ball rates are basically steady, the number of those fly balls going out has increased 34%.

Like fly ball rates, the rate of HR/FB has stayed fairly steady since 2002 (again, the first year for data on FanGraphs). The yearly rates fluctuate, but they're in a tight range between 9.3% and 11.3%. A little historical context is important. You had higher home run/fly ball rates in 2003, 2004 and 2012. Lower rates in 2007, 2010 and 2014. Then, a drastic jumped the last four seasons.

A conversation with Justin Verlander way back in 2016 got me onto this topic. A jump in the home run rate that season had prompted quite a discussion about the reasons why. Justin was one of the first I heard who was adamant that it was about the ball, that the ball was definitely flying differently than in past years. Verlander had allowed 18, 18 and 19 home runs the previous three seasons, averaging 223 innings a year. At the time of our conversation in 2016, he was giving up home runs at a much higher rate than usual, and I was curious if he had some thoughts on why. And, as a matter of fact, he did. He felt like it wasn't a matter of him giving up a lot more fly balls (he wasn't), but that balls were simply carrying a lot further. That balls he knew used to be routine fly balls were now going over the fence. Which prompted me to look up HR/FB rates, which were clearly up sharply. And to this day, this remains one of the strongest pieces of evidence that it's all about the ball.

Any other thoughts on why it's like, the ball, way more than anything else? Exhibit B, which is maybe even stronger than exhibit A, is what has happened in the minor leagues. This was the first year that the major league ball was used in the minor leagues, in both the International League and Pacific Coast League. Early on, there were lots of stories about how home run rates had jumped. I never bothered to check to see where the two leagues ended up. Until the other day. This was rather remarkable. Total home runs, by year, since 2016:





Pacific Coast League





International League





Take another look at that last column. Let those totals sink in for just a moment. In one year, you had a 58% increase in home runs - in both leagues. Isolated power jumped from a three-year average of .133 in the IL to .179. And from .153 in the PCL (3-year avg) to .200. Run scoring jumped 25% in the International League, 19% in the PCL. These are absurd year-to-year changes. Unless there was a league-wide directive for every hitter to change their "launch conditions," I'm guessing that increase of over two thousand home runs (in one year!) was all related to the ball.

Does it matter? I would think that if you're in the talent evaluation business, it matters - a lot.

What the research over the last three years has taught us about the ball: My thinking on this topic has been heavily influenced by three main articles of the many that have been written over the past several years.

Ben Lindbergh and Mitchel Lichtman's research in 2017 found that lower seams added almost three feet to the flight of a batted ball. As did a higher coefficient of restitution. They found a slightly smaller ball added roughly one foot to a ball's flight path. All in all, tiny - but measurable - changes had, at that point, added approximately seven feet to a batted ball.

In March of 2018, Tim Dix and Rob Arthur x-rayed the core of the baseball and found it the chemical composition (more polymer, less silicon) had changed over a four-year period, leading to a core that was 40% less dense. They didn't reach definitive conclusions, but suggested a less dense core could lead to more "bounciness" - i.e., a higher coefficient of restitution. They referenced Lindbergh's and Lichtman's research to remind us how small changes interacting with each other can lead to major changes in how a ball plays.

Then, this past summer, Dr. Meredith Wells examined seam heights and leather smoothness to a degree no one had before. And concluded that lower seams had led to a smoother surface, and that the ball was measurably rounder. The Special Committee of Very Smart People basically dismissed her findings out of hand, which irritated me. This was good research. Wells is an astrophysicist turned scientific researcher. She knows when something is statistically significant. Her research showed the year with the least amount of leather smoothness - the most static friction - was 2014. That season happened to be the year with the lowest home run rate of the last 26 seasons. Wells' research also helped explain why home run rates were relatively stable from 2004-2015.

That's a lot of good research in just three articles. They certainly pointed the way for what researchers could look into in the future, and pointed out the necessity for looking at the interior of the ball, not just the exterior. But it sure doesn't seem like Rawlings or MLB is willing to let its own special commission get access to that information.

MLB keeps repeating that baseballs are within the tolerances for a legal baseball. But remember - you can have two baseballs, one in each hand, and one might fly 49 feet farther than the other. Both within the league specifications for weight, circumference and "bounciness" (coefficient of restitution), and yet one flies almost 50 feet farther than the other.

Baseball has talked in the past about maybe tightening up their tolerances so two legal baseballs might be separated in flight by, say, only 20 feet. Which seems like quite the reasonable goal. What other sport allows for this kind of wide range for how their puck/ball/pelota performs? I can't quite think of the proper analogy. A football that flies 80 yards with the flick of a wrist? A golf ball that allows you to carry the green on a 520-yard par 5?

Did you know golf has a strict standard for how far a golf ball can fly? It's 317 yards, with a tolerance of three yards. Baseball has no legal limit for how far a baseball can be hit, and has a tolerance of 16 yards. Does this make any sense?

Which brings us to...

What baseball could do: Baseball could follow the lead of golf, and use synthetic materials to make a baseball. This is something Rawlings has reportedly suggested to MLB, and MLB apparently recoiled in sheer horror at the idea. And even my first reaction was - "No! Stay natural!" But logic says this might well be an idea worth considering. From an August story in USA Today by Josh Peter:

Like the baseball, the golf ball once was made exclusively of organic properties, including threads of rubber and elastic wrapped around the core. But by the 1960s, rubber gave way to urethane skins and synthetic resin cores, according to multiple accounts of the golf ball's evolution.

Thanks to advances in synthetic materials, (former Rawlings Executive Art) Chou said, today's golf balls perform far better and more consistently than their organic predecessors (emphasis added).

"There's no reason you couldn't do that with a baseball,'' said Chou, who also worked for golf equipment maker Titleist. "I think there's a lot of lessons to be learned by looking at golf ball manufacturing. The way technology has been applied to golf ball manufacturing has resulted in better performance and better consistency. But you had to be willing to accept changes in the traditional way the ball is made.''

Annnnnnd... looks like that's not going to happen. From the same article:

Kathy Stephens, director of quality assurance for Rawlings, said she has talked to MLB officials about the possibility of adding synthetic materials to the baseball in an attempt to make the ball perform more consistently.

"Yes, there are things that could be done, I believe,'' Stephens said. "We've mentioned it, but the tradition of baseball is such that they don't want change.'

And finally, Lloyd Smith of the Sports Science Lab at Washington State University:

"Oh, yeah, they're locked into history,'' he said. "There are features of the major league ball that are characteristic of the way rubbers were produced probably 100 years ago that today are just ridiculous. But they do it the same way so they can say the ball is made the same way.''

Anything jump out at you there? They're making the ball using a "ridiculous" century-old process. "Ridiculous," I'm guessing, because manufacturing techniques have probably improved a bit since 1920.

To review, using the same units of measurement: a legal golf ball has a built-in limit of 951 feet, with a tolerance of 9 feet. A baseball has no legal limit, but right now, tops out at around 505 feet, with a tolerance of 49 feet. I have no idea whether a baseball could be made from synthetic materials for greater consistency. The people who know a little something about how to make a baseball obviously feel it can be. Sure seems like it's worth investigating, doesn't it?

What it all means: My best guess - based on all the independent research that's been done, plus my own personal observations watching several thousand home runs fly the last several years from my perch in the broadcast booth, is that a 2019 ball is probably flying 8-12 feet farther than a 2015 (first half) ball. There are days when I think that's conservative. Whatever the number is, it's significant. It's not helping the big power hitters - they've never had a problem clearing the fences. It's the guys with modest power. You can identify them by looking at guys who have made no change in approach, or have the same mix of groundballs and flyballs, and yet are hitting a lot more home runs (see: DJ LeMahieu, Christian Vazquez, and Roberto Perez, just to name a few).

Can we talk about the weather? Thanks to Robert K. Adair's classic "The Physics of Baseball," we've known for a long time that weather can have a huge impact on the flight of a batted ball. Wind, air pressure, humidity and temperature can all have an effect. Wind has the biggest impact - adding 30-60 feet to a fly ball when it's blowing out, taking an equal amount out of a fly ball when it's blowing in. But how often do we hear about air pressure? Almost never. And yet, all other factors being equal, air pressure affects the flight of a batted ball more than anything else. Air pressure affects air density, which leads directly to what the special commission is talking about - drag.

I don't pretend to be an expert on this. But spend a few minutes reading some of the insights from those who are and you realize how much weather conditions can affect a batted ball. High pressure systems combined with low humidity will absolutely take a few feet (or more) out of the flight of a fly ball. Low pressure systems with high humidity - think summer storms - and the ball is moving through the air with less friction, and is flying farther. You know what we had a lot of this past summer? Rain. From the Midwest to the East Coast, it was one of the wettest summers on record. That's a lot of low pressure.

Temperature has an impact too - Adair said add an extra couple of feet with every ten degree rise in temperature. So a fly ball in 90 degree weather might go an extra 10 feet compared to a ball hit in 40 degrees. I've seen numerous references to how the Cardinals estimated the "postseason ball" was flying 4 ½ feet shorter than it was during the regular season because of increased drag. You know what the game-time temperature was for the last two games in St. Louis in the NLCS? At first pitch, it was 45 and 59 degrees. I'm guessing the average game-time temperature during the summer was a bit higher than that.

The Bill James Handbook has a section on Ballpark Indices every year. It's one of my favorite sections, because what we've learned through the years is that, without major changes in roster makeup or in park dimensions, there can be large changes in how a given ballpark plays season-to-season. But over a three-year period, you get a pretty good feel for whether a ballpark is hitter-friendly or pitcher-friendly.

There are many reasons why there might be fluctuations year-to-year, and weather certainly can be one of those factors. There's a reason Colorado (high elevation = low density = ball flies likes it's shot out of a cannon) and Texas (oppressive heat and humidity and windy as hell) are the two best hitters ballparks over the last three years. (Fun exercise for Rangers' fans: try to predict just how different your new ballpark will play with the roof closed most days next summer. Most indoor ballparks are either neutral for run-scoring, or pitcher-friendly. The Ballpark in Arlington has been second only to Coors Field for run-scoring the last three years).

Teams can also do a lot more to understand how wind affects how their ballpark plays day to day. Because there's a lot going on inside every ballpark on a windy day, with wild differences from ballpark to ballpark. We know on a windy day at Comerica Park, for instance, that while the flags show a stiff wind blowing out to left, at field level, the shortstop and third basemen often feel a strong wind blowing in from left. There's a group called Weather Applied Metrics that's doing some fascinating work on creating real-time graphics on the movement of air inside ballparks (see an example at Given the large impact wind can have on a given day, it seems like every team would want a model of how their ballpark plays on windy days. I'm not quite sure how you would use the information, but it seems like it's a piece of information enterprising hitters or pitchers might use to their advantage.

We all know the weather can be wildly unpredictable. And while its effects are certainly not easy to measure with precision, there's just no question it can have a major impact on the flight of a batted ball. Which is, after all, what we're talking about here. It has to be part of the discussion.

The people on MLB's latest special commission are some of the sharpest minds out there - but their report is far from complete, which they fully admit. And it's puzzling, since so many have done such good independent research the last four years to point the direction for baseball to further investigate the causes behind what really is an unprecedented jump in home runs. You would think the experts working on behalf of Major League Baseball would be able to give us a more definitive answer about precisely what's going on with the key component of the game - the ball.

You don't have to believe that there's some great conspiracy at work here if you question MLB's incomplete findings and Rawlings claims of "no juicing." There are a lot of baseball fans, and more than a few major league players, who just want better answers. That shouldn't be too much to ask.


"These Scientists May Have Solved MLB's Juiced Baseball Problem," by Josh Peter:

"The Juiced Ball is Back," by Ben Lindbergh:

"We X-Rayed Some MLB Baseballs. Here's What We Found." By Rob Arthur and Tim Dix:

"Yes, The Baseball is Different - Again." By Dr. Meredith Wells:

This is a FanPost and does not necessarily reflect the views of the <em>Bless You Boys</em> writing staff.