Celtics get ‘butts kicked’ by Clippers, losing second straight finals preview at home

BOSTON — At one point, the Boston Celtics’ home winning streak had been going on for so long that it became an afterthought. By the time they reached 20-0 at the Garden, it just felt like they might never lose. Since then, it’s two losses in a row to two teams who might be back in this building in June. At least the Denver Nuggets game was close. This was the Celtics’ biggest home loss since Ime Udoka’s first game in charge. It took that team awhile to find its identity, but the Celtics have been an elite team ever since. They’re not supposed to just fall flat at home anymore. Joe Mazzulla said that in the third quarter Saturday…