PORT ST. LUCIE — Tomas Nido’s most common advice to his rookie protégé is “breathe.” It’s Nido’s way of reminding Francisco Alvarez to inhale and slow down as he attempts to handle the nuances that go with catching at the major league level.

Alvarez, 21 years old and the Mets’ top prospect, possesses a powerful right-handed bat that might already be capable of producing solid numbers for the club. But until Alvarez demonstrates he has mastered the art of catching, he is likely to remain at Triple-A Syracuse.

Glenn Sherlock, the team’s catching instructor, has been entrusted with overseeing most of that development. But Alvarez has also turned to Nido and Omar Narvaez this spring for help.

“I tell [Alvarez] when I was his age, I could throw for days and my arm would never get tired, never get sore,” Nido said Saturday, when the Mets lost 4-2 to the Astros before defeating the Marlins 5-2 in exhibition action. “I wish I would have listened a little more to the people that had told me to take it easy. It’s a little harder now to get the engines going. It’s easy for me to say things, but some things you want to experience yourself.”

Narvaez, whom the Mets signed in the offseason to a one-year contract worth $8 million that includes a player option for next season, has worked with Alvarez on waiting for the ball instead of reaching to catch it.

“When I’m working, [Narvaez] is always kind of patient and telling me ‘You do that. You do that,’ ” Alvarez said. “Now I am working with him on waiting a little bit more for the ball.”

Alvarez’s maturity also includes learning the preferences of his pitches. As an attendee at major league camp last season, he began that process, working with the likes of Max Scherzer, Carlos Carrasco, Tylor Megill and David Peterson. This spring he has three new starting pitchers — Justin Verlander, Kodai Senga and Jose Quintana — to whom he must adjust.

Last season, Alvarez got a taste of the big leagues with a call-up from Syracuse in the final week of the regular season. During the stint, he hit his first major league home run and showed enough to convince team brass he was worthy of a spot on the NL wild-card roster. Alvarez received one plate appearance against the Padres and struck out.
“I think I learned a lot in those moments because when we played the playoffs it was a new experience for me and I felt really good in that moment,” Alvarez said. “I see my teammates, how they play, how they prepare for the game. I lived and learned in that moment.”

Alvarez split most of last season between Double-A Binghamton and Triple-A Syracuse. Overall, he owned a .260/.374/.511 slash line with 27 homers and 78 RBIs in 112 games in the minors.

Last weekend, general manager Billy Eppler said Alvarez isn’t a consideration to serve as a full time DH unless he were to sustain an injury that prevented him from catching. That is, the organization remains committed to Alvarez’s long-term growth over a short-term power infusion.

“I like that,” Alvarez said.

But he also knows he could contribute immediately to the lineup.

“I feel really good about my offense,” he said. “I feel like my offense is ready.”

For now Alvarez will continue working on his catching, awaiting the opportunity to wear a Mets uniform full-time.

“There is no doubt in anybody’s mind he is going to be a stud,” Nido said. “The bat is there and that is what I told him from the offseason, even before the season was over: take care of the catching and everything else will be there.”