For someone who never appears flustered in public, who speaks with a knowing smile, Jason Kidd looked uncharacteristically adrift on Monday night following the Nets’ disappointing 108-98 loss to the surging Portland Trail Blazers in Brooklyn. Sitting on the dais, his tie loosened and slightly askew, Kidd spoke haltingly, seemingly searching for answers as to why a team with high expectations was now 3-7, losers of five of its last six games. So Kidd, who chose to coach the Nets as an alternative to retirement, unexpectedly put his head on the chopping block, accepting complete blame for the Nets’ struggles in the game, for why a team that set season highs for points in a quarter (40) and points in a half (63) against the Blazers so utterly collapsed in the third quarter for the umpteenth time this season as Portland (9-2) took control. “Just bad coaching,” Kidd said, so bluntly it almost seemed like he might be joking at first. But he wasn’t. “I take the blame for this,” he went on. “The guys played hard. We got a little stagnant on the offensive end so this falls on my shoulders. We got off to a good start and then that third quarter we came out a little flat and that falls on me.” And with that simple phrase — “just bad coaching”— Kidd immediately put the onus on himself, removing any blame from his high-priced players and inviting criticism from all quarters, a risky decision for someone even as beloved as Kidd.