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TAMPA — The Yankees have a former Red Sox to thank for their new lefty’s bread-and-butter pitch.

Max Fried learned his curveball from his “baseball mentor,” Reggie Smith, when he was a kid attending the longtime outfielder’s baseball academy in California.

Nearly 20 years later, the pitch is a big reason why Fried landed an eight-year, $218 million contract from the Yankees.

“Everything from hitting to fielding to pitching, [Smith] gave me that knowledge,” Fried, a three-time Gold Glove winner, said Saturday. “He showed me a bunch of different grips and taught me how to throw it. I’ve been able to take it from there.”

Fried, who manager Aaron Boone said can “spin it in his sleep,” showed off much of his seven-pitch arsenal Saturday during a live batting practice session at Steinbrenner Field, which included striking out Austin Wells twice.

“It’s always good to get back out there and have the competitive juices flowing, get some guys in the box and see how your stuff’s playing,” said Fried, who was facing hitters for the second time since arriving in Tampa. “It’s early, but got out healthy. Just being able to check all the boxes.”

Boone, who said Fried has been “a sponge” since he joined the organization in December, was encouraged by what he saw in the live session.

“Liked his intent, focus, compete,” Boone said. “Worked on the things he wanted to work on. Stuff’s really good. He’s in a good spot.”

A day after Brian Cashman said he hoped to sign Boone to an extension by the end of spring training, the manager echoed that sentiment.

“I hope we get it done,” Boone said. “No place I’d rather be, obviously, doing it with this team, this organization, in front of this fan base. Hopefully, we do get to the finish line with that. Certainly optimistic and hopeful now.”

Marcus Stroman threw “well over 40 pitches” in a bullpen session Saturday, his first since skipping the first two days of camp.

“[There was] pace to it, stuff was really crisp,” Boone said. “You could tell he’s ready to go. Thought the command was really good, intensity was good, shapes of pitches were all solid. He looks like he’s in a good spot.”

Yerry De Los Santos was in big league camp with the Yankees last year, but this time around he has opened some eyes early.

The reliever, who was added to the 40-man roster during the offseason, made some late-season improvements at Triple-A that showed themselves during a live batting practice Saturday afternoon.

“I thought [he] was really good,” Boone said of the 27-year-old who throws a sinker, slider and splitter and previously pitched in the big leagues for the Pirates.

Jonathan Loáisiga threw about 20 pitches in a light bullpen session Saturday as he continues his recovery from UCL surgery.