Lewis didn't get the correct setup all weekend, hence why he was so far off the pace. He gambled with sticking with one setup hoping he'd learn it, but it just didn't work out.
That said, Rosberg had the race of his life, I've rarely seen him look that comfortable. Although another couple of laps and Ricciardo would've had him I reckon.
Still too many races left to call it. Malaysia could go either way, I'd expect Lewis to do well at Suzuka and COTA, Mexico will be tight, Brazil suits Lewis more, and if it goes down to the final race at Yas Marina I'd put money on Hamilton as he's been there and done it before. Rosberg looks more comfortable then he's ever been, but he's not had a fraction of the issues that Lewis has had this year. Wait until it starts getting tough, then we'll see.