I think that people have to stop comparing OKC's regular season stats with those of Golden State. For Donavan, the regular season was about experimentation. He had to re-integrate Durant (coming off an injury) into a lineup full of players he'd never played with before (Waiters, Kanter, Singler, DJ Augustin, etc.). He tried all sorts of different combinations out there; some worked, some didn't. From the Lee Jenkins article on SI.com (sorry my attempt to post a link was unsuccessful):
"They had a new coach, Billy Donovan, who experimented with lineups, minute allotments, pick-and-roll coverages. He went small, with Durant at power forward and Ibaka at center, and then big, with 6' 11" Enes Kanter alongside 7-foot Steven Adams. He played Durant and Westbrook together the entire first quarter, allowing the bench more freedom in the second, but that backfired so he staggered his stars’ court time. He stopped blitzing every ballhandler, a Thunder trademark, to better protect the three-point line. He emphasized weakside action, an OKC sore spot, to grease movement."
"'I needed to take risks,' Donovan says. 'I needed to get answers. Sometimes you have to throw stuff out there and see whether it’s a good idea or isn’t. I told the guys there would be some rocky roads.' They started 7–6. They lost eight of 12 after the All-Star break. At Florida, Donovan would have said he was playing for March. In Oklahoma City it was for May. Durant required some late-night reassurances, via text, from Presti and assistant GM Troy Weaver: Stay with this, they urged. Execs compared Donovan with a masseur, working out long-lasting knots, a process both painful and productive."
KD wasn't the only one getting impatient; Thunder fans complained incessantly about the lineups, Kyle Singler, Randy Foye, Kyle Singler, Randy Foye, and the defense. In any case, it's now the playoffs, and just like there was "Playoff Tito" there is "Playoff Donavan."