Waters signs six-year extensionChiefs guard makes deal without agentBy ELIZABETH MERRILLThe Kansas City StarIn this time of uncertainty for the Chiefs’ offensive line, one thing is certain — Brian Waters will be in Kansas City for a while. Waters, a two-time Pro Bowl guard, has agreed to a six-year contract extension. Chiefs president/general manager Carl Peterson said Tuesday that the deal was quietly struck in November, with no agents and apparently little haggling. Waters fired his agent roughly a year ago, and when he missed offseason workouts last summer, it was speculated that he was staying away because of contract issues. It turns out he saved a big hunk of money by negotiating on his own, though the Chiefs, per team policy, declined to give terms of the deal. “I think it’s only smart to retain your own best players first, and then if you have the money and the cap dollars (remaining) to go after free agents,” Peterson said. “You don’t want those guys to ever get to the last year of their contract for fear that you might lose them to free agency. “It gives us continuity for the future of the offensive line.” Waters, who was cut by Dallas as a rookie in 1999, was picked up roughly six months later by Kansas City and blossomed into one of the NFL’s elite at left guard. He made his first Pro Bowl in 2004, and the Chiefs have had the league’s No. 1 offense the last two seasons. Waters is the link between the line’s decorated past and its future. With 11-time Pro Bowl guard Will Shields pondering retirement, and Pro Bowl tackle Willie Roaf approaching his final years, Waters will be called upon to help bring along the younger linemen. Shields is expected