WASHINGTON — Before signing with the Nationals, free- agent second baseman Daniel Murphy spoke with Matt den Dekker, his teammate with the Mets in 2013-14.

He must have liked what he heard from den Dekker, who played in 55 games with Washington last season. “He spoke very highly of the clubhouse,” Murphy said.

Murphy, 30, officially signed a three-year deal reportedly worth $37.5 million Thursday and met the media at Nationals Park.

Murphy, who had spent his entire career with the Mets after reaching the major leagues in 2008, said he saw the handwriting on the wall after the Mets traded for second baseman Neil Walker and signed free-agent shortstop Asdrubal Cabrera.

What will Murphy miss the most about the Mets, who drafted him in the 13th round in 2006 out of Jacksonville University?

“It would be the relationships you built,” said Murphy, noting that he came up through the minors with Lucas Duda. “I got a lot of congratulatory texts with guys I used to play with [including Jacob deGrom]. The manager, Terry Collins, reached out to me. I enjoyed my time in New York; some great relationships were made.”

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But Murphy is excited about his new address in the National League East.

“They have laid the foundation of a very competitive team here,” Murphy said. “I have gotten to experience that competitiveness over the last six or seven years being in New York. It is always a tough place to come in here and play. This is the place we wanted to be. I am excited about what the 2016 team has to offer. To be on this side of it is really exciting.”

Murphy, who hit a home run in a record six straight postseason games in 2015 and finished with seven in the first two rounds of the playoffs, was named NLCS MVP after homering in every game in the sweep of the Cubs. He hit .333 in the NLDS and .529 in the NLCS but went 3-for-20 against the Royals in the World Series.

“He never takes an at-bat off,” Nationals general manager Mike Rizzo said. “He is a player who plays the game the right way. We love his attitude, his grit. I have seen plenty of Daniel Murphy in my career, believe me. When the bright lights of not only New York City but of the major-league playoffs come, he shines the brightest.”

Murphy will play second base for the Nationals, though he also has experience at third base, first base and leftfield. He gives Washington another lefthanded hitter in a lineup that includes MVP Bryce Harper, whom Murphy called the best player “possibly on Earth.”

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The Florida native has hit below .280 only once in his career and his 38 strikeouts (in 538 plate appearances) last season were the fewest of any lefthanded hitter who played in at least 115 games. Murphy was an All-Star with the Mets in 2014, and hit .281 with 14 homers in the regular season last year.