Jonathan Papelbon’s days as the Nationals’ closer are over. (AP Photo/Jeff Chiu)

SAN FRANCISCO — Before the Washington Nationals completed their trade for all-star closer Mark Melancon on Saturday morning Pacific time, General Manager Mike Rizzo and Manager Dusty Baker summoned the man Melancon will supplant to Baker’s office to share the news.

Jonathan Papelbon’s identity as a professional baseball player has been tied to pitching the ninth inning. He began his career as a closer a decade ago, as a 25-year-old rookie with the Boston Red Sox in 2006. He is ninth on the all-time saves list and third among active players with 368.

With Saturday’s transaction, the 35-year-old right-hander is no longer a closer — at least with the Nationals — for the remainder of this season. Papelbon, a free agent this winter, said Rizzo and Baker didn’t explicitly tell him that, but they didn’t need to. Papelbon informed them he’s on board with the trade.

“We’re fighting for a championship, this is what it takes to achieve it,” Papelbon said after the Nationals’ 5-3 loss to the Giants on Saturday. “I think everyone being on the same page and playing for a common goal is what it takes.”

Melancon’s addition – at the manageable cost of Felipe Rivero and minor leaguer Taylor Hearn – completes a forgettable week for Papelbon. He appeared in three games in his last week as Washington’s closer, allowing allowed eight runs — seven earned – in one combined inning, good for a 63.00 ERA.

The nightmare began when he blew a tie game last Sunday against the San Diego Padres. On Tuesday, he blew his third save by squandering a two-run lead against the Cleveland Indians without recording an out. The final blow came Thursday when he was yanked in the ninth inning with a three-run cushion after allowing two of three batters to reach base.

“I think anybody losing their job is a hard thing to accept, period,” Papelbon said. “That’s human nature. If you lose your job, would that be a tough thing to accept? Right, exactly. I think that’s just a hard pill to swallow, no matter who you are and what job you’re in. The second part of your question, I think for me I’m just going to have to do whatever it takes to accept a new role and a new challenge for myself. I just take it that way.”

Last summer, Papelbon agreed to a trade from Philadelphia on the condition that he would close, bumping Drew Storen out of the role. A year later, barring an unforeseen development, Thursday was his final outing as Washington’s closer and his role moving forward, he said, is unclear.

“I’m just going to have to do whatever it takes to accept a new role and a new challenge for myself,” Papelbon said. “I just take it that way.”