People try to claim Golden State doesn't have an inside presence. But that couldn't be further from the truth. They have a lot of post up players, some of which have two way skills, such as Maurice Spaights, Festes Ezeli, Bogut, Harrison Barnes (who has a great post up turnaround jumper) and, of course, Draymond Green.
There's a massive difference between "inside presence" and "post scorer."
Speights is a pick-and-pop guy, not a low-post scorer. In 42 games this season, Speights is 7/22 (31.8%) with an average of 0.68 PPP on post-ups.
Ezeli and Bogut are both tough interior defenders, but neither is a significant low-post scoring threat. In 45 games, Bogut is 5/14 (35.7%) with 0.56 PPP on post-ups. In 40 games, Ezeli is 19/49 (38.8%) with 0.71 PPP on post-ups.
Barnes is 25/47 (53.2%) with 1.00 PPP, which is pretty good, but he has 58 post-up possessions in 36 games, which comes out to 1.6 post-up possessions per game. Barnes is enough of a post-up threat that he can take advantage of significantly smaller and weaker defenders, but you can't run an efficient offense through Barnes in the low post. When Kerr was hired, one of the first things he did was to visit every player on the team. Kerr met with Barnes in Miami, showed Barnes how poorly he scored out of isos and post-ups (Jackson put a lot of the second-team offensive burden on Barnes), and told Barnes that wasn't an optimal use of his skills.
Green--10/40 (25%), 0.57 PPP on post-ups--is similar to Barnes, in that he's a post-up threat with smaller and weaker defenders, but not so much otherwise.
Golden State's most dangerous post-up threat is a backup PG (Livingston).
Golden State's best line-up--Curry/Thompson/Iguodala/Barnes/Green--involves no traditional big. They're not running many post-ups with that line-up. They kill opposing defenses by spreading the floor and running high P&Rs with Curry and Green.
If you have a capable low-post scorer with good vision, that's valuable in today's game--but it's also a rare combination. That's one of my beefs with people who argue that Big Man X needs to develop a post game. Aside from underestimating how difficult that is, they also fail to take into account that a post game isn't that valuable if that big man isn't a good enough passer to punish teams for doubling. That's the value of a low-post scoring threat in today's game: drawing double-teams and moving the ball until you get a good look, be it an open 3 or hitting a cutter for a lay-up. But a great P&R duo operates similarly by forcing the defense to either commit an extra defender to stopping the initial action or concede a high-percentage look to one of the P&R guys.
OU doesn't have a great P&R combo, but developing one is more reasonable than expecting a big to develop both the scoring and passing ability to be a true low-post threat.