Pitching at Altitude, Part 1: The General Effects of Elevation

Welcome to a new data-based pitching series about the Colorado Rockies.

Last fall, I evaluated almost every pitcher on the roster during the extended “Crafting a Gameplan” series (which you can find here). This time we’re going to tackle a more widespread, fundamental topic: pitching at elevation. It’s no secret that this is a difficult thing to do, and something the Rockies themselves have grappled with for decades.

Even now, after 30 years, there doesn’t seem to be an obvious answer to pitching at high elevation. What we’re going to attempt to do in this series is use data and physics to truly understand the dynamics that make throwing a baseball at mile-high elevation radically and uniquely different from any other place.

This series will be divided into six parts, each with its own purpose.

• Part 1: The General Effects of Elevation
• Part 2: Mile High Fastballs
• Part 3: Sinkers & Cutters
• Part 4: Breaking Balls
• Part 5: Changeups & Splitters
• Part 6: The Perfect Rockies Pitcher

I hope you enjoy the series and find it informative. Without further ado, let’s begin!

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How do you pitch at Coors Field?

If you asked the average baseball fan, I’m sure the replies would range from “Man, that’s a tough question” to “You can’t.” The ballpark has a fearsome reputation of inflating ERA’s and destroying the confidence of even the best pitchers. Some of that is due to unfortunate timing: The introduction of baseball at Mile High coincided with baseball entering the Steroid Era, when run scoring across the majors jumped to ludicrous levels. The extremely hitter-friendly nature of Coors Field provided a boost on top of the already inflated run totals. As double-digit runs became routine, star pitchers came to the Mile High City and failed, and a decent ERA for a Rockies pitcher usually began with a five.

By the time MLB was exiting the Steroid Era in the late 2000’s, the fearsome reputation of Coors Field was all but tattooed into the brains of fans and players everywhere: the place where pitching goes to fail, a proverbial boogeyman for hurlers across the league.

Even in a more moderate run-scoring era, Coors Field remains the most extreme offensive park in the big leagues. From 2008-22, hitters have slashed .287/.349/.472 there. That is a .353 wOBA (a more detailed version of OBP), 17 points higher than second-place Fenway Park at .336. The difference is the same as the gap between Fenway and 12th place Guaranteed Rate Field; in other words, Coors stands alone as far as supercharged offensive environments go.

But why is that the case? That multi-layered question is the one we’re going to attempt to answer in the first entry of this series. There are many factors that cause baseball at high altitude to make life difficult for pitchers. To make things as simple as possible, I’ve narrowed the list down to three talking points:

• The changes to pitch movement
• The way flyballs carry and the dilemma that causes
• The very dimensions of Coors Field itself

HOW ELEVATION CHANGES PITCH MOVEMENT

We’ll start with this because it’s the single most important effect high altitude has on pitching, in my opinion.

In a game of inches such as baseball, minor alterations to a pitch’s shape can yield dramatically different results. We’ll examine the particular changes to individual pitch types later, but for now it’s important to understand how pitch movement is created. Contrasting that information with the environment present at Coors Field will give us a much better idea as to why pitch movement is so different there. But let’s first get a proper grasp of why and how pitches move.

Pitch movement is physics, and, in simple terms, I’d separate the ways to make the ball move as it heads towards home plate into three categories:

• The Magnus Effect
• Gravity
• Seam Effects

These three work in tandem, of course. Let’s see what we have.

The Magnus Effect

The first element we’ll go over is the Magnus Effect, which is defined as:

The Magnus effect is an observable phenomenon commonly associated with a spinning object moving through a fluid. The path of the spinning object is deflected in a manner not present when the object is not spinning. The deflection can be explained by the difference in pressure of the fluid on opposite sides of the spinning object. The Magnus effect is dependent on the speed of rotation.

In simple terms, the way an object spins as it travels through a fluid has an effect on the trajectory of said object.

For baseball purposes, this is quite intuitive: The baseball is the object, and the fluid is the air the ball knifes through as it moves towards home plate. In essence, the way the baseball spins when it’s thrown changes the way it will move. This applies to many things — the spin direction, spin speed (RPM), spin type, and so forth. And as we’ll see, the type of air its cuts through is important.

The easiest way to think about the Magnus Effect in action is to contrast a four-seam fastball with a curveball.

Because a four-seamer is thrown with backspin, the ball is spun “backwards,” effectively fighting against the force of gravity as it travels through the air and dropping less than it otherwise would.

Many of the great fastballs of all time had this as their key feature. You can really see it below from Justin Verlander. Notice how well he backspins the ball, how it seemingly “rises” as it approaches home plate, and how the batter swings underneath it because it drops a lot less than his eyes and brain told him it would:

On the other hand, a big 12-6 curveball is thrown with topspin, in the opposite direction of a fastball.

This means that, unlike the fastball, the curveball’s spin direction effectively pulls it down, compounding with the force of gravity to create big downward movement.

Another classic example is Adam Wainwright’s big curveball, which you can see below:

There are just two examples, of course; there are many different ways to spin a baseball. There’s also side spin, where the baseball is spun sideways to create horizontal movement, as you can see in this video of Brewers closer Devin Williams’ famous “Airbender” changeup:

Another concept to take consider is that most pitches feature more than just one type of spin.

That Devin Williams changeup, for example, doesn’t have perfect sidespin; there are elements of topspin there, as well as other types.

How do you figure out the degree to which the Magnus Effect is affecting a pitch’s movement? You can mostly do that via the concept of active spin/spin efficiency, which tells you the percentage of a pitch’s raw spin that is directly contributing to its movement.

For an example, if a four-seamer spun at 2400 RPM has a spin efficiency of 90%, that means that 2160 of the 2400 RPM are contributing to its Magnus-induced movement. The other 240 could be some other type of spin that isn’t creating direct movement. In general, the higher a pitch’s spin efficiency, the more it is relying on the Magnus Effect to create movement.

The general point here, of course, is that the direction in which you spin the baseball will have a significant effect in its ultimate movement. But the Magnus Effect isn’t the only thing that will cause pitch movement. What about gravity?

The Force of Gravity and Gyro Spin

Gravity is very straightforward in baseball terms: When a pitcher throws a ball, it will eventually come crashing to the ground.

Every pitch is affected by gravity, and, as we’ve already seen, one can fight the effects of gravity by inducing backspin when throwing a pitch. But most pitch types embrace that gravity to create movement. Breaking balls rely on gravity to a certain extent (some more than others) to create that downward action, and there’s a particular type of spin that allows gravity to have an almost exclusive effect on pitch movement.

Let’s talk about gyro spin for a second.

“Gyro spin” is short for gyroscopic spin, and, for the sake of keeping things simple, think of it as bullet spin, or the way a football spirals in the air when thrown by a great quarterback.

You can really see the spin on this Dinelson Lamet slider below:

See how the ball seems to be spinning around itself, as if it were an endless door knob?

Because of how physics work, by inducing a high degree of gyro spin on a pitch, the pitcher effectively removes more and more of the Magnus effect and allows gravity to take a larger role in making the pitch move in a certain way.

Gyro spin is a part of almost every pitch type, and the amount of gyro a particular pitch has will influence its shape, but it’s especially common in sliders. Theoretically (and in simple terms), a pitch with 100% gyro spin would have exactly zero Magnus-induced movement, and all its movement would instead be created by the force of gravity. We’ll talk more in detail about what this kind of spin profile means later on.

The Power of Seam Effects

Have you heard of the term Seam-Shifted Wake, or “SSW” for short?

SSW is becoming popular in the game as a way to create late, unexpected movement on a pitch by using the positioning of the seams on the baseball as it cuts through the air. Let’s go over this in detail.

As we all know, a baseball isn’t perfectly round: The baseball has seams that emerge from its smooth leather surface. These seams are the key to SSW, thanks to the concept of lift.

To understand this, think of an airplane wing. The top half of the wing is curved, whereas the bottom half is smoother. This means that as the airplane gains speed on the runway, air starts flowing around the wing. That air goes underneath the wing with little obstruction, since that part of the wing is relatively smooth in construction. The upper half, however, is curved, creating a sort of speed bump for the air trying to flow around it. This means the air has to go around the wing, it gets spread out thinner, and its pressure is reduced. And since the pressure underneath is higher than on top, it “pushes” the wing upwards. When the speed of the plane reaches a certain point, then, the force is enough to lift the plane up in the sky.

Picture: Michael Paetzold, Lizenz: Creative Commons by-sa-4.0, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=68538362

The same thing can be applied to a baseball, albeit on a smaller scale.

In our case, of course, the seams on the baseball are top half of the “wing,” and the smooth white leather is the bottom half. This means that, by positioning the seams in a certain manner as we throw the baseball towards home plate, we can create pockets of higher and lower air pressure around it, using aerodynamics to move the baseball late in its flight towards the low-pressure pocket.

This will cause a change in the direction of the spin mid-flight, and you can see it in this Clay Holmes sinker. See how the baseball seems to change spin direction as it approaches the plate?

In essence, that’s what SSW is: manipulating the seams to use aerodynamics, seeking to create sharp, late, unusual movement for the human eye to track. SSW is very popular and common in sinkers, sliders, cutters and changeups of certain spin profiles, and less so in four-seamers and curveballs.

How Magnus, Gyro and SSW Interact With Elevation

Trust me, if that explanation was long, it’s because those concepts will be important throughout the series.

After going over them, it’s time for the money question: How are these concepts affected by elevation?

Coors Field is located at mile-high elevation, which causes significant changes, but for the sake of simplicity, the one that will really matter to us in this instance is this: The air density is lower.

Because of the elevation, the air is effectively thinner. Remember when I wrote that the type of air a ball cuts through is important? That comes into play here. Most of the ways to create pitch movement rely directly on the baseball's interaction with the air it travels through as it approaches the plate. In Denver, however, there is simply less air for the baseball to work with, which means that this dynamic is altered.

• The Magnus Effect is the most affected by this change, resulting in a noticeable loss in pitch movement for offerings that rely heavily on it. We'll see in later entries just what this means for specific pitch types, but for now, you should know that the higher a pitch's spin efficiency, the more altitude will change its shape.
• Gravity and gyro spin, however, are not as affected. Even though, technically, the power of gravity is reduced the higher the elevation, this reduction is not enough to have a significant impact in gyro-heavy pitch profiles. If you ever wondered why the Rockies throw so many sliders as a team, this is a likely reason why. Sliders have, on average, a higher degree of gyro spin than any other pitch type, which means their shape (again, on average) is less affected by Coors Field.
• SSW is an interesting phenomenon at elevation. Because it essentially consists of altering the air pressure around the baseball, a sizable part of its effect is retained. The fact that SSW-heavy offerings tend to feature lower spin efficiency (and, as such, higher degrees of gyro spin) also does its part to ensure that if a pitch's movement is created mostly via a lower efficiency and SSW, it will at least retain some of its qualities.
• Because of all of this, horizontal movement will be noticeably impacted. Horizontal movement is often created through side spin, which is Magnus based. If you look at most charts related to pitch movement, you can expect almost every pitch type to lose some horizontal movement. Sweeping breaking balls will lose some of that sweep; fastballs and changeups with armside run will lose some of that run. We'll go over each pitch type in due time, but know that you should, on average, expect everything at Coors Field to move a little bit less side to side.

This combination of less vertical and horizontal movement effectively makes pitches diverge less from each other at elevation, causing fewer swings and misses and better swing decisions:

Those might not sound like significant changes; batters chase and whiff “only” 3.6% and 5.1% less at Coors than at other ballparks, respectively. But that is typically the difference between the 55-60th percentile and league average.

In a sense, Coors would make a firmly average hitter in terms of chasing and whiffing an above-average one. Coors Field has routinely been a ballpark where strikeouts aren’t very common, thanks to the decreased pitch movement. And it’s not just that contact is more frequent: The results when a batter makes contact are also unique.

YES, THE BALL CARRIES AT ALTITUDE

Every Rockies fan is tired of hearing this, so I’m sorry for having to write it down, but it’s true: The ball flies at Coors Field.

Statcast estimates that, on average, a baseball hit in the air is likely to carry around 20 feet more than the usual ballpark. The only MLB park that even comes close is Chase Field in Arizona (hey, a division rival!), where the ball will carry around 10-13 feet more on average. No other park consistently passes the five-feet mark. This doesn’t mean Coors is a crazy home run park — Coors is a home run-friendly ballpark, but certainly not an outlier. Moreover, it is far more balanced in that regard than it was in the 90’s and early 2000’s. The humidor, introduced in 2002, has played a significant role in that.

Another peculiar aspect of any high-altitude environment is that the air is dryer than it is at sea level. For baseball purposes, this effectively means a normal baseball jumps off the bat more than it would in, say, San Francisco. Combined with the natural extra carry that high elevation creates, you have a recipe for massive home run totals even with the huge outfield designed to keep flyballs in play. Even with the humidor, Coors remains an extremely friendly environment for batted balls whenever they’re put in the air:

The productivity of batted balls is significantly higher than their expected production. You can see what an outlier Coors Field is in this regard, especially when taking the surrounding parks into account.

GABP is one of the smallest parks in the big leagues. Minute Maid has the short wall in right and the extremely shallow Crawford Boxes in left. Fenway has the Green Monster, which means doubles galore, and the Pesky Pole. Compared to these parks, Coors’ outfield dimensions are monstrous, and this is where you really see the impact of the extra carry (along with other things).

There is no ballpark in the majors where flyballs and line drives outperform their expected damage more, period. This is simply part of the deal when you pitch for the Rockies: expect the batted balls in the air allowed at home to create significant damage. Part of that is the extra carry, but the other part is something we’ve already mentioned: the size of the outfield.

THE MASSIVE OUTFIELD ON BLAKE STREET

When Coors Field was built, there was already a very good understanding that flyballs carried a lot further at elevation than they do at sea level.

To combat this and prevent a home run explosion, the proposed solution was rather simple: put the outfield walls really far away from home plate. As a result, Coors Field ended up with massive dimensions — 347 feet down the left field line, 390 (!) to the gap in left-center, 415 to straightaway center, 375 to right-center and 350 down the line in right. No outfield in the majors has more square feet of fair territory. It’s absolutely huge.

www.ballparkpal.com

As we’ve seen, the enormous dimensions do a pretty decent job of preventing home run numbers from exploding altogether — Coors is a homer-friendly park, but not outlandishly so. This is especially true in more recent years with the humidor and the new, taller walls in right-center. As much as some people dislike the “Bridich Barrier,” it’s done the job well.

So what’s the issue with the dimensions, then?

Well . . . outfielders still have to cover all that ground! Everyone thinks about home runs when Coors is brought up, but that’s not what makes it such a challenging pitcher’s park. Coors Field is a great home run park, but it is an outlier BABIP park.

BABIP stands for “Batting Average on Balls In Play,” and MLB average tends to hover around the .300 mark. Since 2015, Coors has generated a BABIP of .332. That is extremely high, and the only other park in its stratosphere is Fenway (at .321), which is another BABIP outlier on its own. No other current MLB park is above the .307 mark.

I’m sure you can picture that BABIP in your head just by thinking about it: those bloops and soft line drives that fall either just in front of, or in between outfielders for base hits or cheap doubles. And the dimensions create other problems on top of the hits. Baserunning becomes “easier,” too. Singles into the gap become doubles for fast hitters, doubles into the gap become triples. Going first to third on a single — something usually challenging to do for most baserunners — is far easier at Coors Field as well.

A PERFECT STORM

The reduction to pitch movement and the extra carry on the ball combine with the quirks of Coors Field combine to create a hitter’s paradise.

In general, you would expect a ballpark to balance itself out to a certain degree. mMst homer-friendly parks also tend to produce lower BABIPs, as seen with places such as Minute Maid, Yankee Stadium, Miller Park, and others. And on the other side of the coin, most higher BABIP parks (Kauffman Stadium, Comerica Park, etc.) tend to produce fewer home runs.

Coors, as per usual, doesn’t follow the rules. It’s the most BABIP-friendly park in the majors thanks mainly to the reduced pitch movement and massive outfield, but it’s also a homer-friendly park because the ball carries more there than in any other place. Batters chase less, make more contact, and the contact they make is boosted.

Then there’s the conditioning aspect, the fatigue of going from sea level back to elevation over the course of the season, and the adjustment process pitchers have to make when they go to Coors Field, and then re-make again when they go back down to sea level.

So, circling back to the question we asked at the very beginning of this piece, How do you beat this? How do you handle this? Can you really pitch well at Coors Field?

My basic answer, of course, is a resounding yes, and the following entries of the series will answer that question directly.

This first piece was needed to set the foundation for many of the concepts we’ll be revisiting many times as we talk about specific pitch types and strategies, scout particular hurlers with arsenals that may be best suited for succeeding at elevation, and eventually put together an all-encompassing plan of attack that could turn Coors Field into an asset instead of a disadvantage. Because, after all, opposing teams who come to play here don’t have the luxury of preparing for the specific challenges of the environment, and they have to deal with them as best they can until they leave town. The Rockies, however, pitch half of their games there. Nobody should know how to handle Coors Field better than they do.

I tend to look at having to pitch half your games at Coors Field in a similar fashion to living in a rough, desolate area without many natural resources. Yes, living there is very difficult, and if you’re not ready to handle it, don’t know what you’re doing, and repeat the same patterns you employed in more-forgiving places, the environment will eat you alive. However, over enough time, you will learn how to handle the challenges. You will think outside the box, you will adapt, and it will be a guarantee that if somebody else from a different place comes to live there, you will outlast them because they don’t know your environment like you do.

And that is what we’re here to do. We’re here to think outside the box and come up with a plan to pitch at Coors Field.

Up next, for Part 2, we’ll be taking a look at four-seam fastballs in particular: how altitude impacts them, how to utilize them, and how to scout and develop good heaters.

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