According to John Shea of the San Francisco Chronicle, Matt Cain's $21 million option for 2018 will not vest if he ends his final guaranteed year on the disabled list with an elbow or shoulder injury. The Giants and Cain agreed to a five-year, $112.5 million contract extension on Monday. The option year converts to a player option if Cain achieves certain benchmarks for starts or innings pitched. If the option does not vest, the Giants can buy out Cain for $7.5 million. If it does vest, Cain has the ability to decline the option and still receive $7.5 million.