The St. Louis Blues got tougher with the free-agent addition of depth forward Kyle Clifford, the kind of player the Avalanche sorely lacks. We previously knew the Avalanche’s toughest player, Matt Calvert, suffered a concussion early last season after inadvertently blocking a shot behind his right ear in Vancouver. We now know Calvert missed the entire seven-game, second-round playoff series against the Dallas Stars with a concussion because he disclosed that Thursday after being asked about the tinted visor he used in Wednesday’s season opener. In the first period of that first game against St.