Third baseman Rafael Devers waves a flag during the Boston Red Sox 2018 World Series Championship parade in Boston. (Bob DeChiara-USA TODAY Sports)

Major League Baseball’s players union responded with outrage Thursday to a member of the Boston Red Sox front office who claimed the league could replace its players in the event of a labor dispute and “the game would go on.”

Bill James, an early adopter of the sabermetrics approach to scouting and a Red Sox special adviser, was debating with colleagues on Twitter about player salaries when he posted, “If the players all retired tomorrow, we would replace them, the game would go on; in three years it would make no difference whatsoever. The players are NOT the game, any more than the beer vendors are.”

The message has since been deleted, but it quickly fired up players and union representatives.

Houston Astros pitcher Justin Verlander asked in a tweet whether the Red Sox could have won the World Series with replacements for Mookie Betts, J.D. Martinez, David Price and others. Retired outfielder Torii Hunter responded to James, “True ballers can’t be replaced but you can!”

MLB Players Association Executive Director Tony Clark called James’s comments “both reckless and insulting” in a statement.

Baseball came within days of using replacement players to open the regular season during the 1994-95 players' strike. Three days before the season opener, Supreme Court Justice Sonia Sotomayor, then of the U.S. District Court of Southern New York, ruled owners could not unilaterally impose a new collective bargaining agreement and bound the players and owners to operating under the expired agreement until a new deal was struck.

The strike-shortened season, teams played only 144 games instead of 162, began on April 25 with regular players.

“The Players ARE the game,” Clark’s statement continued. “And our fans have an opportunity to enjoy the most talented baseball Players in the world every season. If these sentiments resonate beyond this one individual, then any challenges that lie ahead will be more difficult to overcome than initially anticipated.”

Tensions are already high between the labor union and MLB leadership after the 2017-18 free agent signing period saw an unusually quiet market. Teams held out almost until Opening Day before making bids on any of the league’s premium free agents, which drove down the cost of those contracts.

Players, their agents and the union alleged owners were colluding to undervalue free agent deals. Clark called the phenomenon “a fundamental breach of the trust between a team and its fans” that threatened “the very integrity of our game.”

The league responded that it was the “responsibility of players' agents to value their clients in a constantly changing free agent market.”

The dispute seemed to fizzle out once the season began and teams snapped up the likes of Yu Darvish, Jake Arietta, Mike Moustakas and Eric Hosmer. But now relations between the union and at least one front office are growing icy once more. MLB’s collective bargaining agreement expires in 2021.

Read more from The Post:

A greyhound racing ban in Florida means thousands of dogs will need new homes

Alabama fan dies from injuries sustained in bar fight after LSU game

‘Harper’s bazaar has begun’ and so has the Scott Boras Show

ESPN’s Stephen A. Smith says the Wizards' situation is an ‘abomination’ and a ‘disgrace’