The Physics of Roy Hobbs’ Dinger
One of the most iconic scenes in baseball movie history comes at the climax of “The Natural” when Roy Hobbs wins the pennant for the New York Knights with a walk-off home run that destroys the right field lights, causing a chain reaction of celebratory explosions. Obviously this dinger was very unlikely, but was it physically possible?
Keep in mind, players have demonstrated their “light-tower power” before. Most recently, then-Cubs top prospect Eloy Jimenez hit a light in the 2017 Carolina League Home Run Derby, drawing comparisons to the iconic Roy Hobbs himself. So *maybe* it’s possible.
The Specifics
The scene was filmed at War Memorial Field in Buffalo, NY and was set in 1939, four years after Crosley Field became the first MLB stadium to install lights. These lights are a huge part of the scene, so it’s good to know that their presence in this time period is legitimate. But then there’s the issue of hitting them with a batted ball. Let’s dig into the hit itself.
For a home run to be a home run, it has to be hit up. Did Roy do that?
Yes! The side view of Roy Hobbs’ iconic homer shows the ball clearly going up. But what was the launch angle? Keep in mind that 25–30 degrees gives a hitter the best chance of hitting it over the fence.
Looks pretty good. Let’s measure that baby.
Awesome! Looks like Robert Redford did a good job creating an optimal launch angle, something not even an esteemed actor like Daniel Day-Lewis has been able to achieve in any of his “successful” films.
But how about his exit velocity? Well, the film’s many camera cuts and use of slo-mo during the scene make it very hard to approximate exit velocity. Really all we have to go on is the gif above showing the moments just before and after contact. Captured at 60 frames per second, there are about the same amount of frames showing the ball entering the frame as there are frames showing the ball leaving the frame after contact. This suggests that the ball was probably hit about as hard as it was pitched. Ignoring that this ball was probably soft-tossed to Redford from just off-screen, let’s assume that the pitched ball to Roy Hobbs came in around 90mph (which makes sense for a pre-WW2 fastball). I know this is a big assumption, but it’s all we’ve got.
Below is a chart of all balls hit this year at exactly 30 degrees with an exit velocity of exactly 90mph.
Not promising.
But if we’re willing to believe that Hobbs, a player with supposedly prodigious power, hit this pitch with an exit velocity of 100mph, the chart seems a bit more favorable:
Keep in mind, each dot above is where the hit landed. This will be important later.
Given his launch angle and a healthy exit velocity, it is likely that Roy Hobbs would hit a home run. But like, yeah. Of course. We’re not debating if his hit would have gone over the fence, we’re debating if the most iconically colossal hit in film history could have happened in an actual MLB game.
In order to shatter the bank of lights and inspire a generation, what kind of distance are we talking about here?
The Ballpark
Luckily, with the help of a proportional stadium map, we can calculate approximately how far away the base of the lights were in War Memorial Park (which has the same dimensions as the fictional ballpark in the film, of course!!!).
It turns out that the base of the bank of lights, according to this map, would have been 365 feet from home plate. Assuming the profile view of the light bank (in the upper right, covered by the ruler) is proportional and that the outfield wall was about eight feet tall, the middle of the light bank where Hobbs’ homer hit was about 75 feet in the air. Again, that’s believable.
But here’s the thing. The ball was still rising when it hit the lights.
Actually, it appears it was just reaching its apex. So here’s what we know about the HR in question. (This is visualized in the format popularized by Daren Willman of BaseballSavant.com and is not necessarily proportional.)
At this point, it seems like it would take a PhD in physics to figure out if a home run with the hit characteristics depicted in the movie could actually reach a bank of lights 365 feet away and 75 feet up. But thanks to Andrew Perpetua (who I got to meet after SaberSeminar this year) and his Home Run Distance Calculator, we can figure this out without having to consult Neil DeGrasse Tyson.
Here are the inputs I used. Skip ahead if you’re not interested.
Park: Ignore this field
EV: 100, as we estimated earlier
Vertical: 30 degrees (this is launch angle)
Spray: 22 degrees, the direction necessary to hit the light bank
Backspin, Sidespin, Gyrospin, Temp: left default values
Elevation: 0, because the fictional stadium was likely located in New York City which is around sea level
Humidity, Pressure: left default values
Target Height: 75 feet, the height of the light bank
Real Wall Distance: 330 feet, the approximate distance of the fence in front of the light bank at 22 degrees from dead center field according to the War Memorial Stadium map
Real Wall Height: 8 feet, the same approximation as earlier
Wind: 0, I just assumed there was no wind
The Moment of Truth
With all of the appropriate inputs, this program will tell us how far the ball will be when it is at 75 feet above the ground (the height of the light bank).
Unfortunately for Robert Redford, despite his best effort to produce the most legendary swing in human history, he failed. But they could have cast Ken Griffey, Jr. as Hobbs and it still wouldn’t have made a difference.
There are two issues here. First, the ball’s apex appears to be much higher than the 75 feet shown in the movie, topping out around 100 feet. And second, this apex appears likely to occur about 240 feet away from home plate, not the necessary 365 feet to hit the light bank at or before its apex.
Even if Hobbs were to hit the ball at an exit velocity of 150 miles per hour at the observed 30 degrees, the ball’s apex still wouldn’t be 365 feet away from home plate. The idea that a ball hit at 30 degrees off the bat could still be rising when it reaches the light bank in Right Field at War Memorial Park is so preposterous…
…that it doesn’t even fit on our graph.
For a ball to be rising as it reaches this light bank…
…it would have to be hit at an angle much lower than 30 degrees…and harder than a ball has ever been hit by a wood bat.
And to have hit the light bank closer to centerfield, which it appears that Hobbs’ homer actually hit (and I didn’t realize until faaar too late)…
…Hobbs would have had to hit it even harder.
So in short, no. Hobbs’ homer is not humanly possible. According to the Home Run Distance Calculator, a hit at 13 degrees and 150 miles per hour would hit our rightmost light bank at its apex and would go on to land around 550 feet from home plate. Next time we get Roy up to the plate, let’s make sure the Statcast system is up and running for the sake of my sanity.
