A wickedly fast fastball isn’t the anomaly it once was. A decade ago, Major League pitchers threw a grand total of just 196 triple-digit fastballs in a single season. Last year, 40 pitchers collectively threw 1,017.

But while baseball’s hallmark pitch has increased in popularity, it hasn’t increased in velocity.

Consider the confusion over the game’s fastest fastball ever. On paper, the honor goes to Yankees relief pitcher Aroldis Chapman, who clocked 105.1 miles per hour in 2010. But the record could have been set all the way back in 1974. Back then, Nolan Ryan was the first MLB pitcher to be tracked by radar during a game—and while his heater topped out at 100.8 miles per hour, the radar measured Ryan’s ball just before it crossed the plate. Had it eyed the pitch as it was leaving Ryan’s hand (as Chapman’s was), experts believe it might have registered at upwards of 108 miles per hour.

Similar retroactive estimates have put Cleveland Indians pitcher Bob Feller’s fastest fastball at 107.6 miles per hour—and that was all the way back in 1946. Walter Johnson, who played from 1907 to 1927, is also thought to have thrown pitches at a 100 mph or more. All of which is to say: Pitchers have been throwing north of 100-mph for the past 100 years. Over the same time period, advances in training, technology, nutrition, and, yes, drugs, have fueled a dramatic upward trend in world-record athletic performances, from the marathon to the long jump to the 50 meter freestyle. But when it comes to hurling a five-ounce, leather-wrapped sphere as fast as possible, humans appear to have plateaued.

“I don’t see it going much higher,” says biomedical engineer Glenn Fleisig, research director of the American Sports Medicine Institute and an expert in the biomechanics of pitching. “I'm sorry to say that, but I don’t see it happening. Baseball isn’t like other sports, where we see people running faster or swimming harder or whatever, where today’s records are smashing the records from 10 years ago.”