The deal, pending a physical, reportedly is for $140 million -- significantly higher than the deal Yu Darvish signed with the Chicago Cubs last year. The Washington Post was the first to report that Corbin and the Nats had agreed to terms.
The 29-year-old Corbin, an All-Star selection in 2018, is coming off his best season, going 11-7 with a 3.15 ERA while logging 200 innings for the second time in his career. Relying largely on his filthy slider, the left-hander set a career high in strikeouts (246) after making his first Opening Day start for the Diamondbacks.
The Nationals are banking heavily on the trio as they join the Cubs as the only teams in the majors with three pitchers having contracts in excess of $100 million. In 2019, Scherzer will be in the fifth season of a seven-year, $210 million contract signed in 2015. He has a base salary of $30.263 million. Strasburg is entering the third season of a seven-year, $175 million contract he signed in 2016. He has a base salary of $35 million.
After posting the fourth-best ERA (3.63) in 2017, the Nationals' starting rotation took a step back in 2018, ranking 13th in the majors with a 4.03 ERA.
The Nationals' odds of winning the World Series went from 20-1 to 12-1 at the Westgate Las Vegas SuperBook after the Corbin signing.
Corbin, whose deal is the second highest in Nationals history behind Scherzer, had visited with the Phillies and Yankees during free agency, but the Yankees were adamant that they would not agree to anything more than a five-year deal.
He was the second-hardest pitcher to make contact off in 2018, trailing only Blake Snell, and he had the third-best ground-ball-to-fly-ball ratio (1.79) in the majors behind Dallas Keuchel (2.20) and Jake Arrieta (1.80).
"He is definitely legit," an American League scout told ESPN earlier this season. "He commands his fastball, has a swing-and-miss slider and excellent mound presence. ... Assuming health, he's setting himself up for a large payday."
Corbin was in line to be the Diamondbacks' Opening Day starter in 2014, coming off an All-Star season in which he went 14-8 with a 3.41 ERA and 178 strikeouts in his first full season. But he suffered an injury to his throwing arm during a spring training game and had to have Tommy John surgery.
He missed the entire 2014 season and part of 2015, and he went 5-13 with a 5.15 ERA in 2016. He was moved to the bullpen that year.
Corbin, selected by the Los Angeles Angels in the second round of the 2009 amateur draft, had a 56-54 record with a 3.91 ERA in six seasons with the Diamondbacks.
ESPN Stats & Information contributed to this report.