WASHINGTON (AP) — It was a crucial pitch in a game in the early 1990s. A fastball. Away.

When the ball hit Randy Knorr’s mitt, the Toronto Blue Jays catcher moved it back over the strike zone.

The umpire called it a ball.

“Fifty-thousand fans in the stands are booing,” Knorr said. “I knew it was a ball. I was just trying to bring it back over. And he smacked me in the back of the head and said: ‘Don’t ever do that to me again. You know that was a ball, and now you made everybody in the stadium think it was a strike. Don’t do it again.'”

At that moment, at least, Knorr was no Jose Molina.

We’ve all seen it. When a game’s on television, the center-field camera zooms in on the mitt, where the catcher does his best to massage balls into strikes. Sometimes it works; sometimes it doesn’t. Technically, it’s an attempt to cheat, an ingrained and artful baseball deception as old as the neighborhood play at second base.

How much does it influence the game? More than you probably thought. In a sabermetric age where everything is measurable, teams can calculate how many runs a catcher can save by mastering the art of pitch framing. Webpages galore are devoted to the topic, with stat-geeks analyzing the location of every single pitch and tabulating which catchers are best and winning balls and losing strikes.

Teams are keeping count as well. Knorr is now the bench coach for the Washington Nationals, who have devoted more resources to analytics in recent years under general manager Mike Rizzo. This spring training, Rizzo made a trade with the Tampa Bay Rays to acquire Jose Lobaton, in part because Lobaton rated well in pitch-framing.

And where did Lobaton learn the skill? From the guru himself, Molina.

“It’s like those pitches away that when you think that it’s a ball, he can make those a strike,” Lobaton said. “I’ve been trying to do the same. But I’m not like him. I try to be like him, but I can’t.”

A half-dozen extra strikes in a game can make a difference. Rays manager Joe Madden once said that Molina is worth 50 runs per season based solely on pitch framing. Other estimates vary, but mathematical consensus shows that Molina’s subtlety with the glove translates into three to five extra wins each year. That’s enough to win or lose a pennant.

“Any pitch that can change a count that way, whether it’s going to be a 2-1 or a 1-2, that’s the biggest swing you can possibly have right there,” Nationals reliever Drew Storen said. “It keeps you in good counts. It definitely helps you out, if you can get five or six calls that would’ve gone the other way just from the catching framing it.”

Molina’s peers at the top of pitch-framing ratings include his brother, Yadier Molina of the St. Louis Cardinals, and Jonathan Lucroy of the Milwaukee Brewers. All have something in common: soft movements using the wrist and elbow while the rest of the body stays still. Lucroy, who checks in at 195 pounds, has flourished despite a frame not necessarily suitable for framing.

“It’s strange,” Brewers closer Jim Henderson said. “You would think if you miss your spot as a pitcher with that small target you might not get the call, but somehow he makes it work within the parameters of the plate there. So it’s actually amazing how well he does if we screw up.”

Lucroy said it took years to hone the skill after he first paid attention in the minors. It’s a world of difference from those Little Leaguers who yank the ball every which way.

“You can see a big, big difference between guys who can catch and guys who can’t,” Lucroy said. “The pitcher hates it because he wants to be able to pitch and throw, knowing the pitch he throws, that if it’s a strike, it’s going to be called a strike and not taken outside of the zone. … The easiest thing for young players to work on is just keeping your head and body still and just moving your hand. That’s all it is; catch the ball and stop it.”

Or, as Nationals pitching coach Steve McCatty put it: “You’ve got to stick the landing.”

Another pitch-framing master was four-time All-Star Bob Boone. Now a Nationals assistant general manager, Boone would be so intent on keeping still that if the bases were empty he would let the ball glance off his webbing and roll to the backstop rather than move his mitt to catch it.

“I’m going to try to catch it right here,” said Boone, pointing to gap between his thumb and forefinger, “but sometimes I miss ’em. ‘Hey I’m right on the corner, you saw I was on the corner, and he threw it in my glove.’ … If you can get a half-inch on each side and the strike zone’s 20 inches high, that’s 20 square inches. That’s like 4-by-5. All of a sudden the pitcher knows I’ve got that much bigger strike zone.”

Conversely, there are catchers who just can’t sit still. It shouldn’t be a surprise that Jorge Posada, who retired three ago, statistically ranks among the worst pitch-framers in recent major league history. Posada spoke of the importance of the skill while working as a guest instructor with the New York Yankees this spring, but he didn’t venture an opinion as to his own ability.

“I don’t know. I guess people can go back and look and see how they thought I did,” Posada said. “Some guys were better than others, I guess.”