The Giants signed left-hander Madison Bumgarner on Monday to a five-year extension through 2017 with a club/vesting option for 2018 and a club option for 2019. The deal covers Bumgarner through his arbitration years and at least his first year of free agency. "Preserving our core pitching for the long term remains a top priority for the Giants and today's extension certainly helps further that goal," GM Brian Sabean said. "Madison has already proven that he is one of the best left-handed pitchers in the game today and we are confident that he will continue to succeed for many years to come."