LOS ANGELES — The season starts now for Blake Snell, whose return to the Los Angeles Dodgers comes at the right time. Snell has watched just about everything this season as a spectator, and missed enough time that the Dodgers went out at the trade deadline and added another two-time Cy Young winning left-hander to the rotation.Snell is here amid the worst stretch of baseball the reigning back-to-back World Series champions have played this season. He is needed. All is not well for baseball’s resident juggernaut. But at least now they have Snell, and perhaps the game’s most formidable rotation is coming to fruition just in time for another stretch run.“He’s a man on a mission,” manager Dave Roberts said of Snell. Then the left-hander passed his first test.Roberts has been blunt in recent days. The Dodgers have needed better performances than what they’ve gotten of late. They got one on a night where their latest ace du jour came back from midseason elbow surgery.A 5-4 walk-off win over the Kansas City Royals in extra innings secured the Dodgers their first series win in nearly two weeks. The more lasting image will be that of Snell, who showcased his dominance and issued a reminder of just what the Dodgers have missed this summer.“We needed to win tonight, and we needed to win a series, and it started with him,” Roberts said. “So I thought from pitch one, you know, he exuded that. We fed off of that.”