NEW YORK -- Seeking bullpen improvement, the Mets struck a deal on Tuesday with one of the most dynamic relievers on the open market. The team announced a one-year contract with longtime Yankees reliever Dellin Betances, which includes player and vesting options for the 2021 and 2022 seasons. The deal is for $10.5 million guaranteed, a source confirmed, and could be worth up to $14.5 million.

“I love New York,” Betances said in a statement. “I grew up in Manhattan. Went to high school in Brooklyn. Played Minor League ball in Staten Island. Made it to the big leagues in the Bronx. Now, I’m excited to go win a World Series with the Mets in Queens."

A Lower East Side native, Betances, 31, spent parts of eight seasons in the Bronx after the Yankees made him an eighth-round Draft pick out of Grand Street Campus High School in Brooklyn in 2006. A shoulder injury and a partial Achilles tendon tear limited him to a single appearance in 2019; the latter occurred as he jumped off the mound to celebrate a strikeout in his first game back. But Betances expects to be at full strength before the start of Spring Training.

At his best, Betances has as high an upside as any reliever in baseball -- he's a four-time All-Star capable of reaching 101 mph with his fastball. He used that pitch -- along with two distinct offspeed offerings -- to strike out at least 100 batters in five consecutive seasons (2014-18), and reach a career rate of 14.6 strikeouts per nine innings. Only Josh Hader and Betances’ former teammate, Aroldis Chapman, have posted higher rates in baseball history among pitchers with at least 100 innings.

“Dellin is one of the elite relievers in the game with an incredible track record of pitching on the biggest stage and in playoff games,” Mets general manager Brodie Van Wagenen said in a statement. “This is a tremendously exciting gift for Mets fans this holiday season in our championship pursuit.”

The structure of Betances’ deal gives him a chance to rebuild his value after missing almost all of last season due to injury. The contract includes a $2.2 million base salary in 2020, plus a $5.3 million signing bonus. It also includes a $6 million player option for 2021, with a $3 million buyout -- thus the $10.5 million total guarantee. If Betances appears in at least 50 games in 2020, he will also trigger a $1 million player option for 2022 with a $500,000 buyout.

The Mets are mostly worried about 2020, coming off a season in which they finished 25th in the Majors in bullpen ERA. Team officials have spent much of this offseason relaying optimism that Edwin Díaz and Jeurys Familia, both of whom struggled in 2019, will rediscover their previous dominant form this summer. But the addition of Betances means those two won’t be the Mets’ only potential source of improvement.

Betances, Díaz and Familia will form the core of the Mets’ bullpen, along with Seth Lugo, who was moved back to relief work after the Mets acquired free-agent starters Michael Wacha and Rick Porcello.

The team also re-signed Brad Brach to a one-year deal; he, Justin Wilson, Robert Gsellman and likely one other pitcher will fill out the Opening Day bullpen.

Betances’ signing appears to be a direct effect of the Mets renegotiating Yoenis Céspedes’ salary to $11 million from $29.5 million. That restructuring, which resulted from a grievance after Céspedes injured himself on his ranch in Florida, gave the Mets the payroll flexibility needed to make another signing and -- depending on incentives for several players -- stay under Major League Baseball’s Competitive Balance Tax.

To make room for Betances on the 40-man roster, the Mets designated outfielder Sam Haggerty for assignment.