3. Kevin Mitchell (1987-1991)
Wins Above Replacement: 19.1
Mitchell played five seasons with the Giants. A converted third baseman, Mitchell became the Giants everyday left fielder in 1988. In 1989 Mitchell won the National League MVP hitting 47 home runs, driving in 125 runs and finishing with a slashline of .291/.365/.635 for an outstanding OPS of 1.023. He also finished with an incredible 192 OPS+.
Mitchell was traded two seasons later to the Seattle Mariners, but his five seasons were some of the most memorable in team history. Even with all the home runs, Mitchell might be best remembered for his bare handed catch in St. Louis.
Overall, he played 624 career games in left field in San Francisco and had a career slashline with the Giants of .278/.356/.536 for an OPS of .892.