The Boston Red Sox are true contenders for the World Series.

That’s the importance of signing free-agent slugger J.D. Martinez.

Yes, the Red Sox were a good team before Martinez and, as ownership likes to constantly remind fans, the team has won back-to-back American League East titles.

But we’re talking about Boston. Division championships are nice, but there’s that 1-6 record in playoff games the past two years.

Add to that the Yankees factor. In the offseason, New York traded for National League MVP Giancarlo Stanton, who hit 59 home runs last year.

Shots fired from the Bronx.

How would the Red Sox counter?

Mostly crickets.

Boston did re-sign first baseman Mitch Moreland, who hit 22 home runs last year. He was one of the top three Red Sox home run hitters, behind Mookie Betts (24) and Hanley Ramirez (23). That’s 69 home runs from the heart of the order.

Here is what the Yankees have: Stanton, Aaron Judge (52 home runs last year) and Gary Sanchez (33). That’s 144 home runs.

Boston could boast of better pitching, but not by much (3.70 ERA to 3.72), and the Yankees added Sonny Gray last season.

Meanwhile, the defending champion Houston Astros – who led the American League last year with 896 runs scored – improved their pitching. Not only did they acquire Justin Verlander before the trade deadline last year, they traded for Gerrit Cole this winter.

Boston’s response? A lot of hope.

The Red Sox hope their starting rotation remains healthy and durable through the whole season, and that the bullpen improves beyond closer Craig Kimbrel.

Boston hopes Ramirez is finally healthy again, and that its young players keep improving. There is optimism that 21-year-old third baseman Rafael Devers will be productive for a full season.

But while the Red Sox had their fingers crossed, the Yankees and Astros were bolting away – destined for another rendezvous in the ALCS.

The arrival of Martinez changes all that.

Yes, one guy makes the Red Sox lineup dangerous. The 30-year-old Martinez not only hit 45 home runs last year, he led the majors in slugging (.690) and was second in OPS (1.066).

Some envision Martinez batting cleanup, behind Xander Bogaerts. I think Bogaerts (.273 average, 10 home runs last year) is better farther down the lineup.

One potential batting order: Betts RF, Andrew Benintendi LF, Martinez DH, Ramirez or Moreland 1B, Devers 3B, Bogaerts SS, Eduardo Nunez (until Dustin Pedroia returns) 2B, Jackie Bradley Jr. CF and Christian Vazquez C.

Martinez is likely to be the designated hitter most of the time. Boston has three elite defensive outfielders in Betts, Bradley and Benintendi (ranking 1st, 11th and 19th in “defensive runs saved,” according to Fangraphs). Martinez ranked 40th.

If Martinez is primarily the DH, that leaves Ramirez and Moreland platooning at first base. That could get sticky since Ramirez needs 497 plate appearances to kick in his $22 million vesting option for 2019.

For now, Ramirez is saying the right things, telling reporters in Florida on Tuesday: “At-bats are not on my mind. You know what is on my mind? Winning. That’s it.”

Winning comes at a cost, of course.

The Martinez deal, reported late Monday, is for $110 million over five years. He will get $50 million over the next two seasons. Martinez has a player option for 2020 ($22 million) and another option for the 2021-22 seasons ($38 million total).

If he has two banner years, the Red Sox benefit, and Martinez can become a free agent again if he wants, at the age of 32.

In terms of the luxury tax, the Martinez deal puts Boston in a higher tax bracket. The Red Sox were already over the luxury tax threshold ($197 million). With Martinez’s average salary of $22 million, Boston’s payroll is about $233 million – bringing its tax rate to 32 percent. If the payroll exceeds $237 million, the Red Sox would have to pay a 42.5 percent tax, and have its top draft pick in 2019 lowered by 10 spots.

So don’t expect any more big moves by the Red Sox.

The recent addition of Nunez, along with Martinez, means changes to Boston’s roster. One came Tuesday when the Red Sox traded outfielder Bryce Brentz to the Pirates for cash considerations. Brentz, 29, who hit 31 home runs for Triple-A Pawtucket last year, was an insurance policy if Boston did not land a slugger.

With Nunez aboard, the futures of infielder Deven Marrero, catcher/utility player Blake Swihart and utility player Brock Holt are uncertain.

Holt, the 29-year-old veteran, seems safe if he’s healthy. But he’s played 158 games over the past two seasons because of injuries, mostly concussion-related.

Both Marrero and Swihart are out of minor league options. Marrero is strong defensively but not so much with the bat (although he had a .944 OPS against left-handed pitching last year). Swihart is Boston’s third catcher, but is also capable of playing left, first and, maybe, second base. An intriguing player but can Boston keep him?

The fact that we’re talking roster spots for backups, instead of Boston’s power gap, means only one thing:

The Red Sox got their slugger.

Kevin Thomas can be reached at 791-7411 or:

[email protected]

Twitter: @ClearTheBases

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