The Red Sox and Rick Porcello did not make any progress on an extension this offseason, and that means he will test free agency for the first time once the 2015 season is over. This isn't just a guess, it's how things will go, as both the Sox and Porcello agreed that they would not attempt to negotiate an extension once the season begins, according to WEEI's Rob Bradord. Monday is Opening Day, and Porcello has not been extended, so unless something changes in the next few hours after this publishes, Porcello will be a free agent come November.
This isn't akin to the Jon Lester situation, where the Red Sox should have pushed harder to retain him early in order to ensure he would want to stick around. Porcello is new to the Sox, and the Sox new to him, and he's in a position where another high-quality season would significantly alter his free agent value -- Porcello's 2014 was great, but poor defenses have cost him in the past, and the league isn't going to pay him on a hunch that he'll be better with improved fielders behind him. The Red Sox don't (and shouldn't) want to pay that price before finding out if Porcello could be worth it, so they both sides need 2015 behind them before they are willing to negotiate in a way the other side will be open to.
It's unfortunate, in that the Sox could use Porcello in their rotation for years to come -- he'll be just 27 years old during the first year of his next contract, so he doesn't have the same aging risk that many free agent hurlers do -- but it all makes sense given the situation. The Red Sox will have the money to re-sign Porcello come free agency, anyway, whether he shows himself to be more of a mid-rotation arm or one that is worth a $100 million-plus investment. This isn't the end of their discussions, it's just the start of an agreed-upon, lengthy break from them.