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Here’s why you shouldn’t always believe the Statcast home run distance numbers

A couple of Patrick Wisdom homers from last week tell the tale.

David Banks-USA TODAY Sports

We hear of “The Stacast Era” a great deal, now. It rivals “Deadball Era” and “Modern Era” as citations. MLB is careful to state that Statcast’s data are “estimates,” but that’s not how they actually sell it. It’s promoted as sine qua non for on-field performances, down to fractions of inches and of miles per hour. However, one is occasionally inclined to doubt the line, in the manner of the umpire grading sites. On June 30, Statcast laid an eighteen-inches-off-the-plate-called-strike-three whopper on us, and it’s time we recalcitrant old-schoolers had a whole lotta fun with it.

This is a tale of two home runs, both hit June 30, by Patrick Wisdom, the first a dramatic grand slam [VIDEO].

The initial shot by Wisdom is the real subject here. Since the enlargement of the bleachers and the addition of the video boards, on-street home runs at Wrigley have become a rarity. So, on June 30 the ballhawks got a genuine treat, two home runs cleared the left field structures and found pavement beyond. Christopher Morel’s barely cleared, but Wisdom’s overshot Waveland and landed beyond the crosswalk onto Kenmore, we had “Ballhawk Dave” Davison point out the exact spot after the game. (The ball eventually bounded well down Kenmore, almost to the alley north of Waveland, nearly 100 more feet.)

Al Yellon

So few Wrigley moonshots land unobstructed that what Dave pointed out is a valuable landmark. Dave has decades of experience, and his own system of measuring distance. Here we break out our own system, which we have featured in several articles over several years. The first is an overview of Wrigley and environs from Google Earth, the second superimposes a scale of distance, concentric from home plate.

Using a known distance (the LF foul line), we extrapolate the others we will do here, using simple math. We had Dave mark his observed landing spot for Wisdom’s blast. Devious us, we provided him the image without the distance scale.

Now let’s place the landing spots on the general image, and give our own distances for Wisdom’s two home runs. The mark for Wisdom’s second HR, which landed in the bleachers, is taken from video.

Now, let’s give the Statcast data for the two HRs, remembering that they extrapolate final distance for home runs, not necessarily where they first touch an obstruction.

Whoops. Statcast does not allow for prevaling wind, and there was a stiff wind blowing out that evening, but hardly anything that would account for a 40-foot shortfall. The other home run, allowing for the extrapolation, seems reasonable.

So what happened? According to the somewhat limited info Statcast offers on MLB sites, it measures launch angle and exit velocity, and extrapolates everything else from there. Essentially, they take those two pieces of data and build a parabola according to a preset formula. Someone, or something, got one or both of the initial data points wrong.

No harm done, really; as the old baseball saying goes, a 500-footer counts for the same run as an inside-the-park job. But we need to put the formula in its place once in a while. Eyeballs win one, for a change: The Wisdom slam was 442 feet, not 401 as shown here:

Here the article proper ends, but we add a postscript, just for yucks. Besides, having gone through the trouble of digging into the archives for all this stuff, let’s use some more of it.

Two years ago, we marked the 20th anniversary of Glenallen Hill’s celebrated (pre-Statcast) rooftop home run, by giving an educated guess as to its true distance. For that we used Statcast’s own data for the Kris Bryant video board moonshot of September 6, 2015, still the longest Wrigley homer of the “Statcast Era” [VIDEO].

In Bill Jenkinson’s well-regarded book, “Baseball’s Ultimate Power,” he lists Babe Ruth’s home run in Detroit on July 18, 1921 as the longest researchable homer hit during a MLB game, at 575 feet. He uses eyewitness descriptions and old maps to calculate the distance (funny how that works). Using our old KB parabola as the standard for MLB moonshots, what would the Babe have done at Wrigley had he hit that one in Chicago?

For raw distance, we can use our concentric scale; an unobstructed 575-footer, hit to straightaway center (as in Detroit) would land just across the Waveland/Sheffield intersection. Hit to straightaway right field, the Babe’s preferred MO, it would have barely come up short of the Red Line tracks.

How about the center-field scoreboard? Two years ago, we concluded that KB’s home run, hit to proper trajectory, would be well short, but Sammy Sosa’s well-attested 536-footer in 2003 might have scraped the bottom of the board, assuming the parabola is applicable. (See this 2016 article re: the placement of the board in this scale). But the same parabola, at 575 feet, nails it.

It’s up to you to decide whether, after what Statcast has taught us about trajectories, the extrapolation from 1921 has any validity. Also note, by this measure even a 575-footer is heading down (NOT rising) as it leaves the park.

Of course, in 1921, the board, like interleague play, wasn’t even in existence. A pity, on both counts.

Many thanks for your patience and attention.