PHOENIX — Scott Baker was thrilled to be pitching in front of fans for the first time since having elbow-reconstruction surgery. He knows it could be quite some time before he’s doing it on a regular basis. Baker faced six batters in his first start since 2011, in a Chicago Cubs split squad’s 12-6 loss to the Oakland Athletics on Sunday. “It was exciting. I threw some decent pitches, but I also was a bit jumpy and got the ball up,” he said. Baker had been a reliable starter after being taken by the Twins in the second round of …