On a night for round numbers, Buster Posey hit it square. Posey's ninth-inning, two-run homer off Juan Nicasio lifted the Giants to a 4-2 victory over the Rockies on Wednesday night, giving Bruce Bochy his 1,600thwin as a manager and the Giants their 70thof the season, the fifth National League team to reach seven-oh. Tim Hudson collected his 2,000thstrikeout and gave up the 100thhome run on a fly into McCovey Cove, the only run he surrendered in eight innings. But it was Posey's second career walk-off hit that ignited the Giants and their fan base.