Closing lineup should be Cam, Westbrook, Durant, Ibaka and Kanter.
Don't know what the deal is with Donovan & Kanter. I'd understand if teams were just going at him but not many teams really are, & his offensive rebounds/putbacks alone make him worth playing more in the fourth if teams aren't going right at him especially when he's playing well
Bigger picture I'd prefer Serge being put on the same sub pattern with KD & going small with Singler early. Sit KD & Serge around 6 minutes in, bring in Waiters, move Robes to SF, & Singler at PF with Russy & Adams. Run a second unit of Payne, Foye, KD, Serge, & Kanter that way KD isn't forced to run point & do everything.