Buster Posey hit a game-ending two-run homer for his third clout in two nights, sending the San Francisco Giants past the Colorado Rockies 4-2 on Wednesday night for Bruce Bochy's 1,600th managerial victory. Posey sent an 0-1 pitch from Juan Nicasio (5-6) just inside the left-field foul pole for his 18th homer of the year and second career walkoff homer. Santiago Casilla (2-3), who was ill Tuesday, plunked leadoff hitter Drew Stubbs in the back to start the ninth. Justin Morneau then doubled him home to tie the game at 2.