SAN FRANCISCO — Momentum once again lasted just a few hours.Fresh off a blowout win that players and coaches called the best of the second half, the Giants reached second base just twice against right-hander Tyler Chatwood and the Rockies, wasting a gem from Jeff Samardzija. The 2-0 loss made the road to hosting the wild card game considerably more difficult. With four games to play, the Giants trail the Mets by 1 1/2 and lead the Cardinals by a game. Loma Fire Scorches 2,250 Acres, Evacuations Mandatory On the coldest night of the year at AT&T Park, both pitchers took advantage of uncomfortable hitters. Samardzija piled up six strikeouts in the first three innings, but the heart of Colorado's order got to him in the fourth. Carlos Gonzalez blasted a double off the very top of the left field wall and scored on Nolan Arenado's broken-bat single to center.Samardzija looked to be in more trouble in the sixth when a well-placed hit-and-run grounder put two on for Arenado. The longtime Giants-killer hit into an inning-ending double play. The Rockies did add a run in the seventh, however, with a double and single chasing Samardzija. He struck out 11, his high as a Giant....