The ironic thing about S Marquand Manuel losing his starting job to S Atari Bigby is that Manuel did nothing this preseason to lose it. Sure he stunk in 2006, but he hasn't played a lot this preseason because none of the starting secondary has played much this preseason, and he hasn't looked bad when given the opportunity to play. This alone is a huge improvment over last season when he was coming back from the injury he suffered during the Super Bowl and played in only one preseason game, in Cincinnati, where QB Carson Palmer torched him for 3 TD passes.
He would still be the starting safety if Bigby hadn't forced the coaching staff to promote him. Bigby always seems to be around the ball if a receiver gets loose in the secondary and he was a terror when called on to blitz against Seattle.
Now Manuel has to worry about keeping his spot on the roster. With all the cornerbacks playing so well, the Packers might keep one less safety so they can keep one more cornerback, like CB Tramon Williams. Or he might lose his roster spot to one of the other safeties Charlie Peprah, who almost returned an interception for a TD against Seattle.