Nationally, on this country’s preferred medium of conversation, a Padres pitcher had never been trendier. There was Andrew Cashner, blond locks flowing, two-seamers tailing, sliders biting, the pitcher himself flying down the first-base line on a bunt. There were the Dodgers, stateside for another opener, in this one appearing eminently beatable. And there was Seth Smith, a downtown-rocking force in his first Padres at-bat. Chris Denorfia drove in the winning runs of Sunday’s 3-1 victory, but it was Smith, an understated offseason addition, who turned on an eighth-inning pitch and pumped new life into a record crowd of 45,567 at Petco Park. The tying, pinch-hit homer came from a veteran sometimes panned as a fourth outfielder. “One of the reasons we needed that left-handed bat,” said Padres manager Bud Black, “is for situations like tonight.” The Padres had not supported Cashner against Hyun-Jin Ryu, the kind of lefty that so often foiled San Diego last season. While Cashner allowed only a run in six innings -- his fourth time, in four career starts against the Dodgers, yielding a single score -- he remained winless versus Los Angeles. But with Ryu done after seven scoreless, and the Dodgers leading 1-0, the bottom of the Padres lineup drew right-hander Brian Wilson, who re-upped with L.A. for $10 million this offseason.