It isn't working because people are tired of paying $55 or whatever it is per event.
Now people just watch the free events or if they really want to see a PPV go to a bar or something to do so. Everyone is only going to pay out the big bucks for those amazing events when they come along.
UFC 172 was not a great card to sell PPV's. It ended up being a great event but this it what the average person would think when looking at the fights.
Bones vs Teixeira - Bones is good but should win easily
Johnson vs Davis - Isn't he that ww guy and Davis is boring
Rockhold vs Boetsch - Sounds familiar but can't remember who Rockhold is, Boetsch is ok
Miller vs Medeiros - Miller is tough but who the hell is Medeiros
Holloway vs Fili - Who are these guys
The problem is that this card was just not up to top end PPV quality. To bring in the big numbers you need to have either a stacked card or one must see fight and Jones vs Tex isn't that quality of fight.