Shelby Miller is new to the Braves organization, so he’s probably judging Christian Bethancourt based purely on what he’s seen firsthand of the rookie catcher. What he’s seen has been impressive.

On Tuesday against the Red Sox, for example: Miller pitched four scoreless innings, and Bethancourt went 3-for-4 with two long doubles and two RBIs, making him 9-for-25 (.360) with six doubles in spring training before Wednesday night’s game against the Yankees.

“He can swing it,” Miller said. “He’s got a lot of power. The ball he hit to center field, he didn’t even get it that much, and it hit the warning track and bounced up. He’s got tremendous power. Great swing, great player, great catcher.”

Bethancourt also threw out a runner trying to steal second on a strike-’em-out, throw-’em-out double play to end the first inning. Granted, it was the stocky veteran Pablo Sandoval whom he erased, but it was a strong throw nonetheless.

“Live arm, for sure — he’s got a hose,” Miller said. “He’s a good catcher to have.”

It wasn’t a perfect day for Bethancourt, who had a pop foul bounce out of his glove for an error. But all in all a good day for the rangy Panamanian — and an encouraging spring for the long-discussed prospect who’s set to finally get his chance at being a major league lineup regular.

“No doubt I’m feeling good right now swinging the bat,” said Bethancourt, who led the National League in doubles and had four in his past 10 plate appearances before Wednesday. “It’s been a lot of work, and it’s finally showing in the past few years. So keep going.”

A reporter mentioned to Braves manager Fredi Gonzalez that Bethancourt looked more consistent and confident at the plate than last season, when he hit .248 (28-for-113) with only three extra-base hits (all doubles), three walks, 26 strikeouts and a .548 OPS during a couple of stints with the Braves.

“Yeah, and I’m not really concerned about what he does offensively,” said Gonzalez, a former minor league catcher himself. “My concern is taking responsibility and growing as a catcher and handling a pitching staff, which he’s going to have to take care of. To me, I’ve seen a lot of strides there. I’m not really concerned about his offense.”

Bethancourt, 23, was a former No. 1 Braves prospect and was ranked as one of baseball’s top-100 prospects overall for three consecutive seasons through 2014. He was ranked so highly on the strength of his superb defensive skills, and particularly his top-of-the-charts arm strength.

But when he got his first major league playing time last season, there were some conspicuous lapses on defense, an issue that also cropped up from time to time in the minors. Some scouts and team officials thought Bethancourt relied too much on his natural talent and superior skills.

He only caught 29 games at the big-league level, but his six passed balls were tied for the ninth-most among NL catchers and were half the majors’ highest total. Bethancourt also threw out 3 of 13 (23.1 percent) of would-be base stealers. Even given such a small sample size and that fact that some pitchers didn’t hold runners close to the base, that was a low percentage for a catcher with his superior throwing arm and quick release.

This spring has been different. Bethancourt has tightened up his defense and made some strong, accurate throws. Teams aren’t testing his arm much, just as they learned not to run on him in the minor leagues.

“Oh, yeah, I played with him before (in the minors),” Braves shortstop Andrelton Simmons said. “I know the effect it has having him out there. As a base runner, you’ve got to respect when he’s catching.”

Most important for Gonzalez and Braves officials, Bethancourt has made progress at working with pitchers and calling a game. The catcher plays such an important role in controlling a game and settling pitchers, particularly young pitchers, the Braves made it clear to Bethancourt that his priority this spring was to make strides in those areas.

Miller had perennial Gold Glove winner Yadier Molina behind the plate the past two years in his first major league seasons with the Cardinals, so he’s worked with one of the best in a generation. After Tuesday’s game, Miller also praised that aspect of Bethancourt’s game.

“Betty called a great game,” Miller said. “Didn’t shake except for maybe a couple of times. So we were on the same page the whole time, which is great. That’s what you want in a catcher. He did a great job behind the plate.”