The Rock trilogy ends with a whimper.....not a bang. I imagine they jacked the prices up in anticipation of getting around 2011's buyrate. Cena vs Rock II did around the same # of buys as Cena vs Miz featuring The Rock....hmmm.
Well to them it was a sucess due to all the money they made from it because of it being sold out, being in NY and the raised pay per view prices.
The buyrate probably went down due to bad build up to Wrestlemania. People already saw Rock vs Cena last year and the bad build didn't help people want the sequel. The rematch basically went like Rock vs Hogan 2. The first was memorable and the second match up was forgetable.