According to a WWE source I spoke to this weekend, there is a backstage reason why Vince McMahon and the creative team decided to announce that the Rock will be facing John Cena next year at WrestleMania 28 from Miami, Florida. While many critics have said while they look forward to the match, announcing it one-year in advance is too much of wait (in fact, 56% of viewers on WrestleHeat.com said in an unscientific poll that waiting a year is too long of a wait and/or waiting a year killed the buzz a match between the two would have had a month ago; nearly 47% say that while waiting a year is too long, they are still anticipating the match.), McMahon wanted the match announced as soon as possible.
As for the reason, McMahon wanted the match announced while the Rock was working a planned appearance so that he wouldn’t be able to bail on him in the future. In the past few years, McMahon and Rock have come to terms for appearances that never came to be because of other obligations from Rock. However, the feeling is if the match was announced while Rock and McMahon had a working agreement (like last week on RAW), Rock wouldn’t be able to bail on McMahon a year from now if the match wasn’t already booked and McMahon wanted him to come in around WrestleMania 28 time and he couldn’t.