Durant wasn't eligible for the super max(if he actually had gotten it then it would never have been an option for Westbrook since there can only be 1 per team)and not having a player option is nice but doesn't save money. Westbrook would have had to of waited until the offseason just for the possibility. He signed for the absolute max he could have at the time he signed the contract. Ibaka should be paid less than Hibbert.
Why didn't Perkins take a pay cut?
Yes you're right Durant couldn't have gotten that deal it wasn't available then.
I suspect they'll eventually do something with Perkins deal too it's been discussed they may even use their amnesty on him.
Ibaka is a better player than Hibbert, at least for OKC he is. Hibbert is good, and he's 3 years older than Ibaka. There's no way Ibaka couldn't have gotten a similar deal on the open market if he chose to wait for it.
Westbrook knew the super max was available, knew he could very realistically qualify for it, and chose to sign the max deal. There was a long discussion about this on one of the UCLA boards I read at the time it was happening. Kevin Love was mad that he didn't get the full 5 year max offer just 4. Since both guys are former UCLA players it was a hot topic and it was reported there well before it happened that Westbrook was going to take the max deal and not wait because he wanted to give the team a little more flexibilty.
Durant not asking for the opt out was like the 2nd big name guy who made that decision. Perkins also signed a no opt out. IBaka, Westbrook and Collison all took less than they could have likely gotten on the open market if they waited for free agency.
People made a big deal of the Heat players taking less to build a super team they forget they have opt outs.