The agreement comes as a surprise after earlier reports indicating that both sides had agreed to table talks over an extension once the season arrived.
Porcello's deal with Boston won't take effect until the 2016 season, at which point he'll make a total of $20 million through the first two years of the contract and $21 million annually in the final two seasons, according to Alex Speier of the Boston Globe. During the offseason, the two sides avoided arbitration and agreed to a one-year, $12.5 million deal for the 2015 campaign, but both Porcello and the Red Sox had remained mum on any possible extension, even denying that any substantial talks had taken place.
The 26-year-old has yet to make a start for the Red Sox after the club acquired him in December for outfielder Yoenis Cespedes. He is coming off a career-best season for the Tigers in 2014, when he finished with a 3.43 ERA and 116 ERA+ in 204⅔ innings pitched. His clean bill of health likely makes him attractive to Boston -- Porcello has thrown at least 175 innings in every year but one dating back to 2009.
Still, given that he has yet to throw a pitch in a Red Sox uniform, there is some risk in giving Porcello an $82.5 million contract that doesn't begin until next season. Prior to 2014, Porcello's career ERA sat at 4.51 over 149 starts.
Boston GM Ben Cherington clearly believes Porcello's success last season was a sign of things to come, and the right-hander's clean slate of health and youth are certainly factors in his favor. The Red Sox also believe surrounding Porcello with a better defense than he pitched in front of with the Tigers will only aid his performance on the mound. Besides, with Clay Buchholz a free agent after this season, inking Porcello to a long-term deal gives the team's pitching-thin roster some insurance beyond 2015.
If Porcello pitches well again this season, he would be set to earn at least $20 million annually on the open market anyway. The Red Sox were willing to bet on Porcello's talent, keeping him away from free agency while stabilizing their pitching staff over the long term in the process.