You're spot on. As I mentioned and others have suggested as well, the Philly game was the example of how the Giants should be playing.
The Eagles were aggressive the entire game (which ended up being their undoing on the final pick, but that was just a dumb throw) and it almost paid off with a win. The Ravens were consistently aggressive to a much lesser extent.
The problem is that teams and coaches have too much pride to admit that they need to take those risks to win. That's why you see quotes like "if we play our game, we know we can beat them." Well, wrong. We've seen your game all year, and that game is not beating the Patriots, sorry. It takes a lot of guts to come out and play with unbridled aggression knowing that a blowout loss is at least as likely an outcome as coming up with an upset.
Of course, we think that the Giants would acknowledge this, but in their minds they really do have the talent to match up in a conventional game, which I think every rational observer realizes they don't. It's easy to say "they shouldn't want to just keep it close, they should try to win", but they really do believe when they say things like "we match up well with them, etc". It's a tall order to ask a team to swallow their pride and play like the underdogs they are. The Eagles were able to do it, and it almost paid off. If I'm Coughlin, that's my game plan.