The Ravens were 1-2 at the time and were desperate for a win at home. The Bills were 3-0. When the Ravens got out to a quick two-score lead, it turned the gameplan on its head and the Bills were never able to recover.
As we've now seen, the Ravens are a flawed team and are probably going to lose at least three more games this year, including (IMO) this weekend vs. the Chargers. I do think we want to avoid having to play them in Baltimore in the playoffs, though...