Part of what makes the NFL great is that you never know what you are going to see from week to week, even from a team you think you have a handle on. Four weeks into the 2013 season, there has been no shortage of surprises for the 2-2 Ravens. Contributors have come out of nowhere. Talented athletes have disappeared. Heck, they even made a trade. In this week's Five for Friday, Baltimore Sun blogger and reporter Matt Vensel names the five biggest surprises of the first quarter of the Ravens' season.