After an awful first start for Oakland on Thursday, Kendall Graveman did a nice about-face Tuesday. The rookie right-hander, obtained in the Josh Donaldson deal with Toronto, earned his first big-league win, working 51/3 scoreless innings at Minute Maid Park. And for the first time this season, the A’s recorded consecutive victories, beating the Astros 4-0 after taking the series opener the night before. Oakland has thrown a major-league-best four shutouts in nine games. Graveman, who was pitching in low-A ball at this time last season, got a full-bore beer shower from his teammates after his first win. “They poured a lot of beer,” Graveman said. Who got him? “Everyone.” Graveman had allowed eight runs, seven earned, in 31/3 innings against Texas in his A’s debut. On Tuesday, he didn’t breeze through the Astros, per se, but he made good pitches when he had to, and got out of several jams. His sinker was effective once again after he’d struggled to get the ball down in his first start in part because he was rushing his delivery. “I think he learned real quick from that first outing,” catcher Stephen Vogt said. “He called me out there once and said, 'Hey I’m getting a little too quick.’ So, I think it’s just that quick of a learning curve for him. … He’s so smart beyond his years.”