One day last week, as teammates packed bags and readied for the escape from spring training, Gio Gonzalez walked to the center of the Washington Nationals’ clubhouse in Viera, Fla. He fiddled with the stereo until Louis Armstrong’s “What a Wonderful World” blared from the speakers. Gonzalez spun around to face nobody in particular and raised his fist, apparently, in salute to his own musical taste. Gonzalez began his second spring with the Nationals under scrutiny after a report in late January connected him to a Miami health clinic that allegedly distributed performance-enhancing drugs. Gonzalez will take the mound Wednesday night at Nationals Park for his first start of the season as Major League Baseball’s investigation into him and other players named in the Biogenesis report remains ongoing. But from the time he showed up for the new season, Gonzalez has not outwardly allowed the issue to distract him or detract from his effervescence. If the case weighed on him or angered him, or if he felt pressure to preserve his reputation, it has not shown. Gonzalez asserted his innocence on the first day he arrived for spring training, and then he focused on bullpen sessions, Grapefruit League starts and pitching for Team USA in the World Baseball Classic. He received ribbing from teammates about his haircuts, bounded around the clubhouse and smiled constantly. The shadow remains. Gonzalez, for now, has outrun it. “Gio hasn’t changed a lick,” Manager Davey Johnson said. “Every time I’ve see him, he’s grinning from ear to ear and wanting me to grin. He got to me [Monday]. He gave me his words of wisdom. I don’t put a whole lot of stock in that whole thing, anyway.”