A weekly examination of the 49ers' ESPN.com Power Ranking:Preseason: 3 | Last Week: 5 | ESPN.com Power Ranking since 2002The San Francisco 49ers are a Power Rankings reminder to all top teams: Losses are much more damaging than victories are rewarding at the top of the rankings.During their five-game win streak (which included a bye week), the 49ers could only move from No. 8 to No. 5. However, after a one-point loss to Carolina, all that progress was wiped out.