Fresh off a series victory in Phoenix against the Arizona Diamondbacks, the Pittsburgh Pirates will now close their West Coast road trip with a series against the San Francisco Giants. The Pirates (21-17) arrived on the West Coast hoping to hold their ground in a division where no one is losing. They leave it with a chance to do something more: gain ground. As Pittsburgh opens a three-game series Friday night at Oracle Park against the Giants (14-23), the NL Central remains the most surprising race in baseball—every team above .500, every series carrying extra weight. And the Pirates, at 21-17, are right in the middle of it. The math is dizzying. The Cubs have raced out to 26-12 record, setting a pace no one expected. The Cardinals sit second at 22-15. The Pirates are third at 21-17, just two games out of second place and five games behind Chicago. Fourth-place Milwaukee is 19-16. Fifth-place Cincinnati is 20-18.…