Before he closes his book, San Francisco Giants outfielder Hunter Pence stares and stares at a card marking his page.San Francisco Giants' Hunter Pence follows the flight of his solo home run against the Colorado Rockies to lead off the fourth inning of a baseball game in Denver on Wednesday, May 21, 2014.Colorado Rockies' Nolan Areando follows the flight of his walkoff double to drive in two runs against the San Francisco Giants in the ninth inning of the Rockies' 5-4 victory in a baseball game in Denver on Tuesday, May 20, 2014.ADVANCE FOR WEEKEND EDITIONS, MAY 24-25 - In this Thursday, May 22, 2014 photo, Dr. Bill Harrison demonstrates a devise he uses with major league baseball players to improve their vision at the Baseball Performance Academy in San Juan Capistrano, Calif. A hitter will try just about anything to gain even a slight edge on a pitch that arrives in about the time it takes to blink.ADVANCE FOR WEEKEND EDITIONS, MAY 24-25 - In this Thursday, May 22, 2014 photo, Dr. Bill Harrison demonstrates a devise he uses with major league baseball players to improve their vision at the Baseball Performance Academy in San Juan Capistrano, Calif. A hitter will try just about...