Most Productive Player is not the same as Most Valuable Player.
Westbrook has had the most impressive season from a pure counting statistics perspective, but I don't think he's even close to the best or most impactful player from a winning standpoint.
I'd rank him behind LeBron, Curry, Kawhi, Durant, and Harden if we're just ranking who's best in a vacuum. In terms of who has had the best regular season, I think Harden and Kawhi are both ahead of him if you care about defense and whose team is best at, you know, winning games.
Look, it's one of the greatest regular seasons of all time. What's so remarkable about this season is that there are a handful of all-time great seasons by some of the top players in the league.
As I argued in another thread, I'd give it to Harden. A couple rebounds a game should not be the deciding factor here.