I didn't see too many onboards of Hamilton during the race, but it didn't seem smoother than usual. I've seen him drive smoother, going by memory, in the examples I mentioned above (Spa/Canada 2010). But I agree - I thought that Hamilton was doomed to a 3-stopper right after his 2nd pitstop.
Strangely enough I think the oversteer drivers actually had a slight advantage over the smoother drivers in Barcelona. It's a front limited circuit where it's the front left that gets the punishment, so I thought that leaning on the fronts (a la Jenson) would have stressed the fronts more than if you leaned on the rears (a la Maldonado/Hamilton). But hey - what do I know?