The offseason hasn't been to kind to the Seattle Mariners, but it has been for pitcher Felix Hernandez as he's agreed to a five-year, $135.5 million contract extension Thursday.

The extension will keep Hernandez, already under contract to make $39.5 million over the next two years, with the Mariners through the 2019 season.

USA Today first reported the deal, which would be finalized before spring training. Hernandez has two years remaining on his current deal - worth a total of $39.5 million - but according to the USA Today and Associated Press reports, the new contract would go into effect for the start of this season.

Hernandez will make an average annual salary of $27.1 million over the extension, the highest average salary given to a pitcher in baseball history -- aside from Roger Clemens' $28 million prorated salary in 2007.

Hernandez has become the face of the franchise the past few seasons. Signed as a 16-year-old out of Venezuela in 2002, he has been raised and groomed in the organization. Along the way, he established himself as the team's best pitcher, winning the American League Cy Young Award in 2010 and signing a five-year, $78 million extension in 2010.

He posted a 13-9 record in 2012 with a 3.06 earned-run average in 33 starts. He led the American League with five shutouts, while ranking second in innings pitched (232) and complete games (5), third in strikeouts (223) and fifth in ERA. He also threw the 23rd perfect game in major league history on Aug. 15 against the Tampa Bay Rays.

Hernandez will anchor an inexperienced Seattle rotation that likely will include 24-year-old Blake Beavan, 22-year-old Erasmo Ramirez and second-year Japanese starter Hisashi Iwakuma.