CC Sabathia was in his first full pro season, playing with Cleveland’s Class-A affiliate in Mahoning Valley, Ohio, in 1999 in the New York Penn League when he first started pitching with Victor Martinez behind the plate.

Sabathia pitched just six games with the Scrappers, but he still recalls the bond he built with the 20-year-old Martinez and how valuable that became when the pair was reunited in Cleveland in 2004.

“Me and Victor would hang out, go to dinner,’’ Sabathia said this spring in Tampa. “We got to know each other off the field. I realized then how important that relationship was between me and who was catching me. It definitely helps me when I’m pitching.”

For that reason, the 38-year-old Sabathia has kept up the tradition of getting to know his battery-mates and believes that’s made him a more successful pitcher.
“I go out to dinner with them to learn about different things — not about baseball,’’ Sabathia said. “It’s never about baseball. It’s about getting to know them as a person.”

The benefits come later. And it’s why Mets pitching coach Dave Eiland called the dynamic between a pitcher and his catcher “probably the most important relationship in sports between two players.’’

“If you get in tough times and a guy needs to tell you something, he won’t have a problem doing it and you’ll listen,’’ Sabathia said. “In a tough spot, I want to throw a certain pitch and they come out and say, ‘No, this isn’t the right pitch,’ I’m able to trust that because I know the guy. I know he put in the work and did the studying. If you don’t know your catcher and you don’t trust him, if you don’t have a personal relationship and he comes out to the mound and tells you to throw a slider, you’ll say ‘Hell, no, I’m throwing a fastball.’ It helps when you have two minds out there instead of just one.’’

That bond comes over time, and it’s one of the aspects pitchers and catchers work on during spring training — when they can.

“The catchers, they’re part of the pitching staff,’’ Eiland said this spring in Port St. Lucie. “They’re the busiest people in the building if they’re doing it right.’’

And that includes being part teammate, part psychiatrist.

“You have to find out what makes each guy tick,’’ said Eiland, who previously served as the Yankees pitching coach. “Whether to push them or use kid gloves. [Jorge] Posada was really good with [Andy] Pettitte. They would lock horns during the game. Andy needed that. A.J. Burnett, not so much.’’

The challenge increases when a pitcher is acquired during the season.

Last year, J.A. Happ was traded from Toronto to the Yankees in July and had little trouble adjusting to his new surroundings. The left-hander went 7-0 with a 2.69 ERA in 11 starts with the Yankees, pitching effectively with both Austin Romine and Gary Sanchez behind the plate.

Happ is back with the Yankees, having resigned in the offseason and said that despite his success in The Bronx last season, he’ll benefit from more time with the two backstops this spring.

“It usually takes five or six games to learn a guy a little bit,’’ Happ said. “Romine, [Kyle Higashioka] and Sanchez were great and able to shorten the learning curve as best as we could. We had meetings before all my starts to cut down on the period of adjustment, but it was still there.”

Happ pointed to more chats at the mound than he would have liked.

“If you don’t have that communication, they’re not gonna know what you want and they’re gonna make assumptions,’’ Happ said. “I felt like last year, every game was so important when I got here. You don’t want to be shaking your head [at a sign] and wishing you had talked about something. I don’t like to call catchers out to the mound because it breaks up your rhythm, but I’d rather do that than not get the results you’re looking for.”

As the role of analytics becomes more important, catchers are often tasked with tracking more information than ever before, whether it’s about their pitcher or the opposing lineup. Romine, though, said it’s not all that complicated with the current Yankees’ staff.

“[The information] could be a lot, but with these guys, they’re here for their own reasons,’’ Romine said. “With most of them, you know how they’re getting guys out. [Aroldis Chapman] throws hard. [Chad] Green can throw his fastball by anybody. [Adam] Ottavino has his slider.”

His job, Romine says, is to get to know what each pitcher is most comfortable with each day — a process that begins when pitchers and catchers report in mid-February.

“It’s a constant thing for me,’’ Romine said. “You’ve got to talk to them. You’ve got to catch them. You’ve got to pick their brain and find out what their strengths are, how they like to pitch. The mentality of who they are seeps over into how they pitch.”

One of Romine’s goals each spring is to get to know all of his pitchers better.

“It’s separate from baseball,’’ Romine said. “Sometimes, you’ve just got to talk to them and you form a different relationship with each guy. That’s what a lot of spring training is about. Whether you see them in the hall or anywhere else, you find out who they are, what they’re working on so you can keep them going in the right direction.’’

For Sabathia, those off-field conversations involve everything but baseball.

“I’ll talk about soccer, football, life, but not baseball,’’ Sabathia said. “When I’m sitting next to you on the bench, that’s when we talk baseball and what guys are throwing. And then when we go out there, I know we’re good.”

And Romine takes that responsibility seriously.

“They’re noticing what we do,’’ Romine said. “They’re trusting us to call their game. They want to know we’re doing our homework to call a good game. In a lot of ways, they’re trusting us with their career. You never want to mess that up.”