SAN FRANCISCO – The first game of any NBA team’s preseason schedule can bring heavy legs from an intense week of training camp, and rust still needing to be scraped off. The Warriors’ oldest player didn’t appear to have any issues in either category. Al Horford, 39 years old, was sharp and spry in the Warriors’ 111-103 win against the Los Angeles Lakers on Sunday at Chase Center. And he fit like a glove on his new team after spending the last four years with the Boston Celtics. Coach Steve Kerr was effusive in his praise of Horford after the win, and those same sentiments remained after reviewing the film. “Al just never seems to make a mistake,” Kerr said Tuesday after practice. “He just brings everything you want. There’s size and athleticism, and shooting ability and passing. He makes the game really easy for everybody.” Entering his 19th year as a pro, Horford isn’t as easy on himself as his new coach and teammates have been. But even he could acknowledge what everybody saw. The transition from the Celtics’ system to the way the Warriors operate was as smooth as anybody could have...