BOSTON — Just as the designated hitter still promotes debate 43 years after it was first introduced, there appears to be a modern baseball subject that some folks will never agree on but isn’t going away:

Defensive shifts.

Just this past week, Yankees manager Joe Girardi said he would ban shifts if he were baseball commissioner. The comments came a day after Nathan Eovaldi lost a no-hitter when a harmless-looking ground ball to shortstop went for a single because the Yankees had shifted their shortstop out of position.

What’s ironic is that the Yankees are one of the industry leaders in using the shift. In 2015, they reconfigured their infield 1,133 times, which was the fifth-highest total in baseball. And this season they used the shift 224 times going into Friday, which again placed them fifth.

Love the shift, hate the shift.

“I just think the field was built this way for a reason, with two on one side and two on the other,” Girardi said before adding, “As long as it’s legal, I’m going to play it.”

The actual commissioner, Rob Manfred, speculated last year about declaring shifts illegal in off-the-cuff remarks before backtracking. Like the DH, shifts are here to stay — even if teams are taking vastly different approaches to how often the tactic is used.

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Across town from the Bronx, the Mets are among the teams that employ the shift as little as possible. The Mets shifted 81 times going into Friday, which is next-to-last in baseball. Last season, they were 27th out of 30 teams with 506.

Why the disparity? One reason is the Mets have the No. 1 strikeout staff in baseball with an array of hard-throwing starters plus closer Jeurys Familia. Batters are less likely to pull a 97-mph fastball, so the need to overshift to the pull side is lessened.

“We approach it the way we approach everything else, which is we’re not looking at what other people do,” Mets assistant general manager John Ricco said. “We’re looking at our team and what the numbers show against our type of starters. So that may evolve over the year. It’s looked at on a day-by-day basis.

“We try to look at every piece of data we have and put our players in the best position to make a defensive play. We’re trying to look at every factor and we’re constantly learning, too. There’s no hard and fast ‘we do this and we’re going to do it.’ It’s a lot more subtle than that. We may end up shifting more or less. We do take into account our pitchers. We’re not going to say Noah Syndergaard is the same as any other righty.”

Ricco also said manager Terry Collins has the right to call off a shift if he feels the game situation doesn’t warrant it. While Girardi compared the tactic to “an illegal defense, like basketball,” Ricco pointed to another sport.

Mets videos

“Teams are starting to treat it a little more like the NFL does,” he said. “Loading up the field against certain packages. Almost looking at defense the same way. In the NFL, they go to a dime package on third-and-long. They move their players around. That’s kind of what we’re doing here.”

Front-office types know they’ll never convince fans (or sports writers, or announcers, or your grandfather) that the tactic overall saves more hits than it allows. But they do try to get pitchers to at least understand the reasoning behind the shifts.

“It’s our job to give them the numbers and give them the data on a regular enough basis that they have confidence in the numbers,” Ricco said. “You want to make sure you’re doing it in an educated fashion. You have to convince guys, keep explaining it to them. The guy who has given up that ball on the other side of the diamond where there is no fielder saying, ‘My third baseman should have been there.’ ”

As for Eovaldi, he didn’t fret when Nomar Mazara of the Rangers snuck a ball past the shortstop position for the first hit of Monday night’s game leading off the seventh inning. Not much, anyway.

“When it was hit, I thought it was an out,” he said.

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Love the shift, hate the shift.