While the ghost of Red Auerbach has to be shedding major tears given the sad state of the Boston Celtics, the Mavericks weren’t interested in having any pity for one of the NBA’s proud organizations. They simply slammed the Shamrocks. And, even though the Celtics in no way resemble a team that anybody in the NBA would want to measure themselves against, the Mavericks nonetheless did what they had to do and ripped apart the Celtics in the second half before easing off the gas pedal in a 102-91 win at TD Garden. The gift-wrapped victory was the Mavericks’ fifth in a row, their longest winning streak since they won six in a row in February 2012. Who cares if it came against a Celtics’ team that looked woefully outmanned and one that many insiders expect to make major changes before next week’s trading deadline. It was a sharp start to the three-game road trip that will close out the pre-All-Star portion of the schedule. And, by the way, it keeps the Mavericks on schedule for finishing this stretch of the schedule the way they wanted. It was late in January when they got together after a particularly painful loss and decided that the last three weeks or so before the All-Star break required their utmost attention, particularly on defense and with the rebounding. It’s paid dividends. Big time. “There are encouraging signs, but there’s no way we can exhale or start feeling too good,” coach Rick Carlisle said. “The games are just too important. We’re working on being a more together team, which we have been the last few games. We just got to continue it.” The Mavericks survived a listless first half when they held the Celtics to 27.1 percent shooting and still were only ahead by six points. In the third quarter, the Mavericks’ lead went to 16 and it topped out at 24 before the Celtics ate into it during garbage time.