I could be wrong, but I think that was a young Packers line, not yet the dominant unit they became. It was the year after the Ravens Super Bowl, so a 2001 regular season game. By the end of the year, that result make more sense, but at the time everyone on the line was very young. Flanagan had returned from about four different leg surgeries and Rivera had gotten settled into his new spot at RG and quickly became the best lineman on the team until Cliffy got up to speed.