I think the only other real contender for MVP is Harden - so answer me this: who would be worse without their respective MVP Candidate: the Rockets? or the Thunder? I think if your answer is the Thunder, WB is the MVP. (Anderson and Trevor Ariza are, 11th and 14th on the present 3Pfg% chart for all players). Eric Gordon, his other teammate - is 4th, tied with IT.
I'm going to modify your question slightly -- which team would be better with an average starter in place of their superstar?
The reason I do that is because I think it makes more sense to think that way. Most teams are going to look desperately flawed if you just remove their central piece and don't replace him with anybody. Realistically, the question of how much a star improves his team is not how bad his team would be without him, but rather how bad his team would be if they had somebody entirely ordinary in his place.
With that in mind, here's how I think about it.
A league average starter at the "lead guard / offensive creator" spot is probably somebody like Jrue Holiday or Dennis Schroder.
So, which team would be worse off with Schroder or Holiday in place of their superstar?
Well, I think both teams would be bad, but not horrendous. Both teams have good coaches and the infrastructure to play a certain way.
Still, I think the Rockets would be worse because without Harden, they would probably be a middle of the road offensive team at best. Their defense would become a much bigger issue in that case.
My guess is they'd be something like a 30-35 win team.
The Thunder with a Schroder / Holiday type would be toward the bottom of the league offensively, but they might also move the ball more and involve talented players like Oladipo, Kanter, and Adams more heavily.
At the same time, they would likely be at least as good defensively as they are now, which is to say a top 10 defensive squad.
Given that, I think they'd be in the mix with teams just outside of the playoff picture. Certainly not a bottom feeder.
Overall, I think the rosters around Westbrook and Harden are comparable; the Thunder are more oriented toward defense and rebounding, while the Rockets are oriented toward shooting and offense.
Given that when you look at both teams
with their stars, the Rockets are a considerably more dangerous team than the Thunder, I think the argument is weighted in Harden's favor.