The 1-3 Knicks, who lost to the lowly Bobcats last night, were already playing some pretty mediocre ball before losing Tyson Chandler, the team’s starting center and best defender, to a fractured fibula for four to six weeks. Now they’ll be counting on Andrea Bargnani, a seven-footer whose inability to grab rebounds seems to defy the laws of physics, to help fill his shoes. These are dark times.