Nationals hire Red Sox’ Paul Toboni as head of baseball ops

TORONTO — Paul Toboni, a Red Sox executive who ascended from intern to assistant general manager in less than a decade, is leaving the organization to be the Nationals’ head of baseball operations, league sources confirmed on Wednesday.

It is a significant loss for the Sox’ front office, at a time when chief baseball officer Craig Breslow wants to hire a GM to be his second in command. Toboni, a source said previously, had been a heavy favorite for that promotion.

But the Nationals — who fired longtime GM Mike Rizzo and manager Dave Martinez on July 6, immediately after the Red Sox swept them — selected him for an even bigger job at the outset of their franchise reset.

Toboni, 35, becomes the fifth former Red Sox executive to currently run another club, joining Jed Hoyer (Cubs), Mike Hazen (Diamondbacks), Ben Cherington (Pirates), and Dave Dombrowski (Phillies). And Chaim Bloom is taking over as the Cardinals’ boss after this season.

Toboni joined the Red Sox as a baseball operations intern in 2015. He was hired as an area scout — evaluating amateur talent ahead of the draft — at the end of that season. He became the assistant director of amateur scouting in 2016, director of amateur scouting in 2019, vice president of amateur scouting and player development in 2022, and assistant GM in November 2023.

In that role, he has served as a best lieutenant to Breslow, who came aboard in October 2023.

Since Toboni’s hiring wasn’t yet official, Breslow declined to comment Wednesday before the Red Sox played the Blue Jays at Rogers Centre.

Manager Alex Cora described Toboni last week as “ultra-aggressive with his ideas.”

“He’s a sounding board to a lot of people in the front office,” Cora said. “I wouldn’t be surprised if at one point they’re going to be running their own organizations.”

Eddie Romero, another Red Sox assistant GM, also interviewed with the Nationals.

It’s not clear if the Nationals also intend to hire a GM as Toboni’s No. 2, or if Toboni will take on the GM title.

Also uncertain is the status of Bedford native Mike DeBartolo, who has served as the Nationals’ interim GM. He has been with Washington since 2012.

In addition to raising questions about the Red Sox potentially losing more front-office or coaching talent to Washington, which will be looking for a manager, Toboni’s departure would seem to complicate Breslow’s search for a GM.

“The right thing for the organization, the right thing to help our leadership team, is to have a clear No. 2,” Breslow, who has not had that in his first two years running the Red Sox, said this month. “The responsibility I have is to find the best person.

“I have a pretty good idea of what will benefit the organization. We spent the last two years … trying to get ourselves set up with an eye on this sustainable organizational health that we talk about all the time. Finding someone who can continue to push us forward and advance this vision will be really helpful.”

The Red Sox will not face righthander Shane Bieber, who has been effective since returning from injury a month ago, in the series finale Thursday.

The Blue Jays bumped Bieber back a day to Friday against the Rays, creating an opening Thursday. Toronto’s options include righthander José Berríos, who was recently demoted to the bullpen, as well as lefthander Eric Lauers, who has bounced between the roles all year. Or they could go with a bullpen game.

The Sox, meanwhile, are sticking with righthander Brayan Bello in his regular-season finale. He has a 5.85 ERA in four starts this month.

Carlos Narváez made his 104th start at catcher Wednesday, when he was behind the plate for ace Garrett Crochet. He has long since surpassed his previous career high of 65 starts. “Obviously, defensively, this kid is special,” Cora said. ”But I think he’s stayed the course. Through the ups and downs of the second part of the season, he knows what he needs to do behind the plate.” … Righthander Dustin May threw two innings of live batting practice on Tuesday, Cora said. If May continues to feel well in his comeback from right elbow neuritis, that could put him in play to return to the active roster — albeit as a reliever — this week.

Tim Healey can be reached at timothy.healey@globe.com. Follow him @timbhealey.