Why Are Some New Statistics Embraced and Not Others?

For the casual, uninitiated baseball fan who tunes in every once in a while, this season’s home-run calls must sound as baffling as a Pentecostal sermon to an unbeliever. A baseball broadcast is, as much as anything, a string of synonyms in a familiar, comforting cadence. Words like ‘‘dinger,’’ ‘‘laser’’ and ‘‘punchado’’ take years to embed themselves into the game’s collective vocabulary, and there’s a graveyard full of home-run and strikeout calls that failed to do so or have fallen out of fashion. (My favorite among the dead: the understated yet effective ‘‘tater’’ for a home run.) Statistics have an even harder time gaining mainstream acceptance, so it must be strange for a newbie to tune in to a Yankees game this year and see Aaron Judge, baseball’s largest son, hit a towering shot into the bleachers and hear the commentator say something like, ‘‘Wow, that ball traveled out of here with an exit velocity of 115.3 miles per hour!’’

Judge, who has become a star this season and a major focus of some emerging statistical language, currently boasts the highest percentage of batted balls whose exit velocity exceeds 95 miles an hour. And according to Statcast, a network of cameras and fussy sensors that track nearly every movement on a baseball field, Judge’s home run against the Orioles in June that played on a weeklong loop on social media traveled 495 feet. (A blast hit in July by Whit Merrifield, the Kansas City Royals’ second baseman, was reputed to have gone 561 feet — just four feet shy of Mickey Mantle’s apocryphal 565-footer in 1953! — but was largely dismissed as a Statcast error, because it is pretty much impossible for anyone, especially middle infielders, to hit a baseball that far.)

Judge, a rookie right fielder, is not only one of the top producers in the categories of exit velocity and home-run distance; he leads the American League in home runs too. For a vast majority of baseball fans, the differences between these ways of describing what Judge is doing don’t really matter — at least not yet. Exit velocity and home-run distance can be thought of as ways to quantify how hard a player hits the ball. These calculations — along with another stat, launch angle, which describes the gradient at which a ball leaves a bat — mostly provide a sense of how much influence a batter exerts over the path of a baseball. But the ‘‘HR’’ as a stat roughly captures the same thing, plus it tells you the outcome. Balls smashed with high exit velocities and high launch angles can still turn into outs.

On most fronts, the decades-long war over how to best explain what happens on a baseball field has been won decisively by the nerds; analytics, also known as sabermetrics by baseball people, have definitively changed the way teams build rosters. But even though fewer baseball writers, managers and players crankily dismiss analytics, statistics like FIP (Fielding Independent Pitching, which tries to measure a pitcher’s effectiveness by taking into account the fallibility of his teammates in the field) and UZR (Ultimate Zone Rating, one of several attempts to quantify defensive performance) don’t get a lot of prime real estate on the Jumbotrons. Nor do they generate much discussion on sports talk radio, where ideas like ‘‘locker-room presence’’ and ‘‘clutch hitter’’ still prevail.

Baseball isn’t the only sport that suffers from this disconnect between how its top evaluators see the game and how fans do. Cameras that track players’ movements have also been installed in N.B.A. arenas, for example. But while the data they generate — like the total mileage a player runs in a game or the frequency with which he drives to the basket — have helped coaches and team executives better evaluate talent and performance, these stats still remain abstractions to most spectators. So why has exit velocity, which doesn’t really seem to tell us anything we can’t see with the naked eye, spread so quickly, including to video scoreboards in several major league ballparks and the commentary on highlight shows? Or to put it more broadly, why do some stats catch on while others stagger off into the cemetery of useless acronyms?

‘‘Bill James had a great line,’’ Tom Tango, the senior database architect of stats for MLB Advanced Media, told me. (If James is largely considered the godfather of sabermetrics, Tango could be its Michael Corleone.) ‘‘If you have a metric that never matches up with the eye test, it’s probably wrong. And if it never surprises you, it’s probably useless. But if four out of five times it tells you what you know, and one out of five it surprises you, you might have something.’’

As the fight between the quants and the traditionalists has worn on for the past 30 years or so, small but consistent concessions have been made on each side. Old baseball heads grumpily admitted that walks were probably better than sacrifice bunts and that the number of wins shouldn’t be the main criterion for a starting pitcher. And the quants began to think of ways their work could match up better with what was seen on the field.

Tango’s job is to take data and turn it into baseball stats that not only capture what’s actually happening on a baseball field but also engage the average fan. Exit velocity is really not all that new — radar guns trained on pitch speed have long been able to pick up the speed with which the ball leaves the bat. But nobody thought much about it until a few years ago, when a handful of teams started installing camera and radar systems to track action on the field better, like an outfielder’s speed to a fly ball or how quickly a ball leaves the park. The popularity of exit velocity this season has been reinforced by circumstance — barring a severe outbreak of anemia, major league batters will hit more home runs this season than any other year on record. Judge’s first-half power surge and the almost comical distance many of his shots have traveled demanded some better metric that could stand in for exclamation points.

As part of his work, Tango takes raw data from Statcast and tries to figure out how to create appealing statistics that satisfy the ‘‘four out of five’’ rule. The exit-velocity numbers were compelling enough and showed that there seemed to be a cutoff point at which a hard-hit ball usually turned into a base hit. But the data also showed that the chances of a ball leaving the ballpark were dependent on the launch angle — roughly speaking, a ball that leaves that bat faster than 95 miles an hour at a launch angle between 25 and 30 degrees will usually clear the outfield wall. (That same ball hit at 12 degrees will most likely result in a sharp line drive.)

Tango knew that there would be no easy way to get the public to embrace some wonky combination of launch angle and exit velocity. So, in more accessible terms, he created a stat that evokes how many times a batter hits the ball on the barrel of the bat. But technically speaking, ‘‘barrels’’ counts the number of times a player hits the ball over 98 miles an hour at an angle that will result in a hit more than half the time.

In the 40 years that have passed since James published his first treatise on baseball statistics, the debate between the quants and the traditionalists has been dour and joyless. The nerds yell about objective truth; the cranky aesthetes praise ‘‘putting the ball in play’’ and ‘‘gritting out wins.’’ Sabermetric advances, as a result, tend to feel like tablets being handed down from the mount. Nobody has fully figured out how to turn sabermetric innovations into a more exciting product on the field.

Barrels and exit velocity already have had an effect on how teams rank players, and Tango and his colleagues will continue to figure out ways to apply new data sets in their player evaluations, but exit velocity’s staying power in popular culture may ultimately hinge on how it’s packaged and pushed out to the public. It is a fun stat, perhaps the only metric developed post-‘‘Moneyball’’ that hasn’t been explained to the public in a condescending whine. The terms are simple and consistent with what most fans already know — a pitcher with a reliable 95-miles-an-hour fastball throws hard; a batter whose exit velocity regularly reaches 98 miles an hour hits the ball hard. Anything over 100 is worthy of attention. (Round numbers, as always, rule.) And unlike catchall measures of a player’s value, whether Wins Above Replacement (WAR) or Value Over Replacement Player (VORP), exit velocity is free of the stink of the actuarial tables deployed by team executives, or worse, fantasy-baseball players. It simply confirms, on a repeating, easily digestible basis, what you see on the field. And unlike on-base percentage (OBP), which rewards the boring walk, exit velocity coincides with something most fans come to the ballpark to see.