Yes, on-base percentage really is more important than batting average, according to ESPN senior baseball writer Keith Law.

Law’s new book, “Smart Baseball: The Story Behind the Old Stats That Are Ruining the Game, the New Ones That Are Running It, and the Right Way to Think About Baseball,” is a three-part primer for fans new to advanced stats with an eye to the future for those in the loop.

“This is how people in the industry think.” Law said. “The refusal to learn is unfathomable to me.”

Law, whose book is available April 25, has a point. Today, all 32 teams use tools such as MLB Statcast, which measures everything from a pitch’s spin rate to exit velocity off of the bat, to evaluate players.

But stats he considers flawed or useless, like a pitcher’s win-loss record, still dominate discussions.

“We should be done with that by now,” Law said. “We should be long past that.”

Front offices are forging ahead. Law suspects a combination of old-school scouting and analytics produced New York’s recently rebuilt ball clubs.

“Teams have recognized value in being efficient with your dollars and being able to put a more accurate number on the value a player provides,” he said.

But it doesn’t take high-level calculations to catch some of New York’s hottest prospects, like Mets Triple-A shortstop Amed Rosario.

“He’s going to come up at some point this year clearly,” Law said. “He’s going to destroy Las Vegas.”

Law also has high expectations for Vegas first baseman Dominic Smith.

For the Yankees, he sees superstar potential in Gleyber Torres but believes it’ll be Clint Frazier who puts on pinstripes first.

“That guy probably spends a pretty big chunk of the season in the majors,” he said.

Traditional scouts shouldn’t be abandoned, Law argues. Instead, they should apply their decades of expertise in new ways.

“They have a mental database of players too, and they’re going to make connections in their minds with past players that we’re not going to be able to do analytically,” Law said.