It's probably premature to put a line on an NFL game at this time.
The draft hasn't happened, unforeseen injuries haven't occurred and no one really knows how new coaches will adapt to their new teams.
Even so, it's probably too hard for oddsmakers to stay away once the Week 1 schedule comes out. Shortly after the schedule was released Wednesday night, Covers.com placed lines on each game, including the season-opener between the Ravens and Bengals.
NFL opening lines per @LVSuperBook - Jaguars at Eagles (-11), Raiders at Jets (-4.5), Bengals at Ravens (-2.5), Bills at Bears (-6.5)— Covers.com (@Covers) April 24, 2014
With the game at M&T Bank Stadium, the Ravens are 2.5-point favorites. In most circumstances, a team gets three points for being at home. So essentially, the early thought process is that this game could go either way.
I'll stay away from any predictions at this time. It's too early and too ridiculous to get into that when a 53-man roster isn't close to being set.