@Martin Argerami,
The classic game rating of Carlsen and Caruana is very close (3 points difference!). But rapid game rating is another story. The rating point difference is a whooping 100 points. Carlsen's strategy throughout this whole tournament was along these lines - beat me if you can in classic. If you don't, I will sweep you off in the rapid games. And he did exactly that. Sure, Caruana is a quality player; but playing under time pressure, not to mention pressure in playing for World ChmapionshiopChampionshiop, is a totally different thing.
So, Carlsen has no need to risk anything; (yet, it was Caruana who looked more happy after draw was agreed in game 12. This is quite understandable since Carlsen had the advantage in the game.)