Russ plays like the better player, but I don't think he actually IS the better player. The reason Durant won the MVP was because people got a really good look at just how great he was. Which didn't happen until Russ went down.
Don't get me wrong, Russ is probably a top-5 player in this league. His athletic ability alone allows him to do things that other people just flat out can't and frankly, there is no point guard that can truly match up with him physically outside of a prime/fully healthy Derrick Rose and even then, Rose isn't as physically strong. If we're going by stats, then getting more boards than someone comes down to effort and aggression, which might be two of the best three parts of Russ' game (the other being athleticism). Westbrook's very disposition screams alpha dog, though. And that might make him the better player in the eyes of others.
Just ask yourself this question. Which OKC team would win more games: One without Durant or One without Westbrook. I'd take the Durant team.