LAS VEGAS — A year ago this month, holding his son Bronze, Kansas City Chiefs quarterback Patrick Mahomes spoke candidly with family members backstage after appearing on Jimmy Kimmel Live. “Got the real challenge coming this offseason,” Mahomes said, as shown on Netflix’s “Quarterback” series. “Thought winning the Super Bowl was hard. Two of these bad boys … “ If only he knew what awaited next. The Chiefs went through hell and back this season, faced with self-inflicted mistakes and personal demons. They made their way through Buffalo and Baltimore in hostile road environments during the pla…