Bryce Harper will earn at least $21.625 million next season. (Katherine Frey/The Washington Post)

The Washington Nationals and Bryce Harper agreed to terms on a salary of $21.625 million for the 2018 season, eliminating the need for arbitration and promising Harper the highest salary for an arbitration-eligible player in major league history. The deal, announced on a sleepy Saturday afternoon at Nationals Park, eliminates the need for what both sides expected to be a complex negotiation this winter and reduces the risk of hostility between the former MVP and the team that drafted him as he hits the open market after next season.

“I think it’s huge,” Harper said. “We’re able to go into the offseason and worry about different things. We’re able, as a team and this organization, to just go out and not have to worry about me going into arbitration for another year or anything like that.”

Nationals General Manager Mike Rizzo and Harper’s agent, Scott Boras, began discussing the possibility of a 2018 deal as they negotiated Harper’s 2017 salary during arbitration this past winter. Both sides were open to a two-year deal then, but they settled on Harper’s salary of $13.625 million for this season and left 2018 negotiations for later. Those talks resumed in the last few weeks, as Harper told Boras to do a deal for 2018 if the Nationals were still willing. As Harper began the season looking more like the 2015 version of himself than the 2016 version, the Nationals were willing.

“We don’t have to worry about things after the season,” Rizzo said. “There will be no anxious moments, arbitration moments and that type of thing.”

Arbitration can be contentious, a somewhat awkward process in which a team benefits from playing down the abilities of a player it would otherwise aim to please. But for Harper, the process is particularly complicated, largely because of a lack of precedent from which to draw a salary figure.

“He’s a very unique player,” Rizzo said. “That’s difficult to come up with a person that’s 24 years old with an MVP on his belt and a bunch of all-star games and Silver Sluggers — lot of hardware at 24 years old, and with the arrow still pointing north.”

When it comes to Harper, the arrow has always seemed to point to the winter of 2018, when he will probably become the most high-profile free agent since Alex Rodriguez, a star in his prime almost certain to break records for contract size and shape. Speculation has always swirled around his long-term future but began to intensify after his MVP season. Will he stay with the Nationals? Or will he go to one of those big markets Harper always seems to treasure? The answers to those questions did not necessarily become any clearer after he agreed to his 2018 salary, and both sides insist they did not discuss anything beyond his arbitration-eligible years.

“These conversations were more about ’17 and ’18,” Boras said Saturday, when asked about how this deal affects Harper’s future. “It wasn’t really about anything after that.”

“We were trying to get this portion of it done. So we didn’t discuss anything beyond 2018,” said Rizzo, who said he and Boras had always been more focused on getting through Harper’s arbitration years.

“I think 2018 is a ways away,” Harper said. “I’ll let Scott and all those guys take care of that. Solidify what’s going to happen now … the rest, I’m not really worried about that right now.”

In other words, Harper and those around him continue to avoid making any comment about his future. Saturday, he raved about Rizzo and the Lerner family, said his relationship with both of them has grown over the years, and said “I love walking into this clubhouse every single day and putting my Nationals uniform on.”

The deal, the terms of which were first reported by Jon Heyman, will make Harper the second-highest-paid player on the Nationals’ 2018 roster as it stands right now. It bests the next-largest deal for an arbitration-eligible player — Mike Trout’s $20.083 million on his long-term deal with the Angels — and the highest one-year deal for an arbitration-eligible player, which was David Price’s $19.75 million with the Detroit Tigers in 2015. It also represents a raise of $8 million on Harper’s current salary, and therefore a willingness on the part of the Nationals to commit major money to a player who has one outstanding year to his name along with a few great, but not legendary, seasons.

“We thought it was a shared-risk negotiation and contract for ’18. On our side, we have a risk if he doesn’t perform at an optimum level. He has a risk that if he does perform at an optimum level, he’s left some money on the table,” Rizzo said. “And we think those are the best deals, where we have shared risk and there’s a trust and a confidence between the team and the player.”

Perhaps that confidence, and the Nationals’ willingness to negotiate during the season before Harper proves he really is the MVP version of himself for more than a month, will foster goodwill as Harper heads to free agency. Perhaps it will not matter at all. But by agreeing to his salary for the 2018 season, Harper and the Nationals ensured their next negotiation, should they have one, will be one for a deal that would keep him in D.C. beyond 2018.