Adam Lind, center, playing for the Seattle Mariners last May, is congratulated by Nelson Cruz, left, and Kyle Seager following a three-run homer. (Otto Greule Jr/Getty Images)

WEST PALM BEACH, Fla. — As their pitchers and catchers streamed into their spring training home ahead of their official report date Tuesday, the Washington Nationals made a significant addition to their bench by agreeing to terms with power-hitting lefty Adam Lind, according to a person familiar with the situation. The deal, which becomes official once Lind passes a physical, will pay Lind $1 million in 2017 and includes a mutual option for 2018. If the option is not exercised, the Nationals will owe Lind $500,000, meaning the Nationals could pay $1.5 million for one season of a player who hit 20 homers in three of the last four years.

If Lind passes his physical, he will become the fourth outfielder and backup first baseman, likely bumping similar big lefty bat Clint Robinson from the Opening Day bench. While Robinson provided outfield depth and an everyday-ready backup to Ryan Zimmerman at first base for the past two seasons, he fared far better in 2015 than he did in 2016. Lind, on the other hand, has had six 20-homer seasons and hit 20 home runs in 126 games for Seattle last year.

In addition to bolstering the Nationals bench, Lind also provides everyday-capable insurance behind Zimmerman, who has neither stayed healthy nor produced like the steady all-star he once was for three seasons now. Should Zimmerman get injured, Lind could slide in to everyday duties and provide the kind of power for which the Nationals would have relied on Zimmerman. Should Zimmerman struggle again, Lind could slide into a first base platoon, though no one with the Nationals has said as much yet.

But Lind might also help keep Zimmerman on the field, because with reliable power available to play first, Manager Dusty Baker can rest Zimmerman more often to maintain his recently fragile health. Lind could also occasionally play left field to spell Jayson Werth, another veteran Baker likes to monitor closely. If both are healthy and producing, Lind becomes an asset off the bench. He has a .309 average and .921 OPS in 108 pinch-hit at-bats. He will combine with Chris Heisey, who is the active leader in pinch-hit home runs, and Stephen Drew, who hit eight home runs in 143 at-bats last year, to make the Nationals bench even more formidable than it was in 2016, when Baker and GM Mike Rizzo praised the group from start to finish.

The addition of Lind fits with what has been a slow and relatively low-profile offseason for the Nationals, filled with more tweaks than head-turners — though their trade for Adam Eaton ensured they did have one of those. But he provides an indisputable upgrade and replaces some of the power lost when Wilson Ramos and Danny Espinosa headed elsewhere. The Nationals had a strong starting lineup, loaded with veterans and former all-stars. They lacked depth, though they do not anymore. All three of their free agent signings this winter have added to the bench.

Lind is 33, and a veteran of 11 major league seasons, the first nine of which he spent in Toronto. He jumped to the Brewers in 2015 and the Mariners in 2016. He is a .271 career hitter, and though his average fell to .239 last season, he struck out in just 20.7 percent of his at-bats, less often than both Zimmerman and Werth. For reference, Brandon Moss, another Nationals target for the role Lind will now fill, struck out 30.4 percent of the time.

So the Nationals continue to buff up their roster, which could undergo still more changes before Opening Day because this winter’s markets moved slowly and unpredictably. Stars like Matt Wieters are still available. Potential relief help could still be found via trades. The Nationals, for example, traded Jerry Blevins to the Mets just days before Opening Day two years ago.

But even if the Nationals stopped now, Lind solidifies their lineup in a way Drew and Heisey could not have alone. He provides proven power and a decade of experience behind a recently beleaguered first baseman, a 39-year-old left fielder, and off the bench. Lind’s arrival also indicates that the Nationals, uncharacteristically quiet for much of this offseason, might not be done building their roster just yet.