PORT ST. LUCIE — Cespe-beast.

The goal this spring for Yoenis Cespedes has been defined. The Mets are trying to make him a more refined hitter without taking away his natural aggressiveness. More contact. More walks. More success.

To that end, hitting coach is Kevin Long is making key points in batting practice in the hopes they will carry over into the games.

Watching Cespedes hit at Tradition Field in David Wright’s group the last two days, the positive changes are already taking place.

Cespedes is focusing on driving the ball up the middle and to right-center. With his immense strength, the results have been remarkable. On Wednesday he drove a pitch high over the batter’s eye in center field. On Thursday he was crushing balls to center and right-center throughout the session.

All with one goal in mind. To make him a more dangerous hitter.

“He’s all in,’’ hitting coach Kevin Long told The Post on Thursday. “Cespedes is very receptive to advice, to working on stuff, he’s great to work with. He’s a baseball player.’’

Then Long smiled and said, “Remember what buttered your bread.’’

Cespedes, 30, knows what buttered his bread to the tune of three years, $75 million.

Said second baseman Neil Walker of the Cespedes BP show, “It’s a very good learning curve for everybody who is watching. It’s not about hitting homers, it’s about using the big part of the field, staying inside the ball, and when you watch it, you realize it’s not about taking 100 swings, it’s about taking five swings with a purpose.’’

Remember, this is Cespedes’ first spring training with the Mets, the first time he has had the chance to work with Long in such detail. Cespedes came to the Mets on the fly last July 31 and there was no messing with success.

Not with a .942 OPS, including 17 home runs and 44 RBIs, in 57 games.

But pitchers made adjustments to Cespedes. In the last 20 games, he hit .219 with 17 strikeouts and two home runs. Cespedes managed one extra-base hit in the NLCS and World Series, a double, and batted .150 in the World Series. A left shoulder issue didn’t help matters, of course, and it is the classic small sample size.

He was bound to cool down.

Cespedes is putting on a clinic so far.

“You don’t need to hit pull-side home runs in batting practice,’’ Long said. “If you want to drive the ball, drive the ball to center field and right-center field. I told him I don’t want to see pull-side home runs, unless it presents itself.

“Center and right-center is where he is working, you just need to stay on the ball and feel like you are behind the baseball. He’s got tremendous power to all fields so it is not like you are taking something away from him. You are just working more within the scheme.’’

At one point during the workout on Wednesday, Wright asked Cespedes to hit a home run over the scoreboard in left field.

To which, Cespedes responded, “No, K-Long won’t let me.’’

Asked about his approach, Cespedes said he is focusing on driving the ball up the middle. “It feels good,’’ he said of the work.

Earlier this week, Hall of Famer Mike Piazza said he had a “good talk’’ with Cespedes about cutting down his strikeouts and taking more walks.

“He was really receptive,’’ Piazza said. “He’s a good guy. I enjoyed talking to him.’’
Because of the Cespedes car show, the county-fair pig, his love for golf and round waffles, there has been a sideshow atmosphere to this Mets camp, but Cespedes is working hard on making adjustments, all the while showing off his incredible athletic skills.

The last two days he has briefly taken ground balls at shortstop, making a couple of spectacular plays, several times racing in to barehand the ball and firing to first.

Noted Wright of the main deal, batting practice, “K-Long has us working on not just hitting the ball up the middle, but hitting it hard up the middle. It makes my hands work and gets my swing in the right path.’’

Same goes for Cespe-beast.