Interesting. I can see the argument for doing that. So is the debate who is easier to replace? or or which is easier to replace with someone who would compliment the remaining two.
To me it comes down to this: Which player do I fear facing the most. As inconsistent he can be shooting the ball, and as selfish he can be looking for his own shot, and as cocky as he can be in Subway.......I would keep Westbrook. He is so disruptive for opponents. He is a great competitor.
If I was OKC and had to choose one over the other, I keep him over Harden.
But I would have kept Harden too. you build around all three.