I don't think he's "trying to make him a four", so much as he realizes that their rotation, as currently cons uted, should consist of nine. But within' that nine, there's only three bigs and none of them play major minutes, so someone has to eat up some minutes at PF and given his size and rapidly declining athleticism/speed/quickness, in addition to erratic shooting, it makes sense that he be that someone the majority of the time.
This reminds me of '08. I think they know they absolutely must acquire a fourth big, even if it means paying a higher price than they'd prefer (the only one from the top nine who might get traded is Neal; I'm speaking more to picks). It's not like it hasn't been a need in recent years, but they were still holding out hope that Bonner would come through in the playoffs or that they could get away with Blair for a few minutes. It's clear they've now accepted that neither of those two can be an option. They don't even want to have to play them in the regular season anymore, even with all of the maneuvering that the current big rotation requires.