There’s an axiom among NBA-types that the only thing that travels well is defense. Defense is just about the only thing the Charlotte Bobcats had Friday. That and Josh McRoberts’ wide-open 3 from the corner that clinched an 86-80 victory over the Cleveland Cavaliers. The Bobcats are 5-4 because they guard relentlessly. Their shooting was bad again (40 percent from the field) and for once they didn’t get 30 or more trips to the foul line (20 Friday). But they found a way to close down the Cavs (40.5 percent), outscoring Cleveland in a second-half span of 13 minutes by 23 points. Point guard Kemba Walker, who shot terribly since injuring his left shoulder five games ago, did just about everything else with seven assists, five steals and five rebounds. “I’m not shooting the ball so well (16-of-78 over five), but my teammates keep encouraging me to attack,” said Walker (12 points). “Basketball is not just about making shots. It’s grabbing long rebounds, it’s guarding Kyrie” Irving. Irving, the top pick of the 2011 draft, played in a protective mask after breaking his nose in a loss to the Minnesota Timberwolves. He finished with 18 points and 10 assists, but was 5-of-16 from the field and committed six turnovers. Walker made the play of the night with just over a minute left and the Bobcats leading by six. He drove hard to the rim, drew the attention of Cavs center Anderson Varejao, and whipped a pass to the corner, where McRoberts nailed a 3-pointer. “I drew his defender and he was out there kind of wide-open,” Walker said. McRoberts said it meant a lot that Walker trusted him with that pass, after McRoberts missed eight of his previous 11 shots. Trust is a big factor in this team’s improved play.