No, they haven’t lost their minds. These small moments of apparent wardrobe examination are just byproducts of modern baseball. As loads of data have revolutionized the sport and the level of sophistication required to play each position has risen, more and more teams are employing positioning cards to guide their fielders through every game.

Infields have been altering their positioning based on their opponents for decades, but the frequency and precision have risen exponentially in recent years. Now the Yankees’ outfielders, too, carry cards with information on how to best situate themselves. Pitchers and catchers also use them, but as a reference guide for their complex signs. Some, like Sabathia, stash their cheat sheets in their caps, and others in their pants.

“People think I’m pulling my cellphone out of my back pocket,” outfielder Clint Frazier said.

Even after sending 18 players to the injured list this season, the Yankees, whose game on Thursday against the rival Boston Red Sox was rained out, have a 36-19 record, second best in the American League. The Yankees’ defense, despite some uneven stretches, has remained solid despite all the turnover.

For their outfielders, the cards tell them where to play relative to their teammates, based on a rival hitter’s tendencies versus a right- or left-handed pitcher. Reggie Willits, the Yankees’ first base coach and outfield instructor, said the cards are based on information provided by the team’s large analytics department. He adjusts them based on how opposing hitters have fared recently.

“Sometimes we’ll see stuff midgame, and the outfielders will make their adjustments,” Willits said. “When they come in, they’ll tell me what they saw, and I trust our guys, and they’ve got good instincts.”