Whilst the Roosters did fantastically well last year, I think they are going to find backing up a premiership is harder than winning it. There really is a reason why no team has gone back to back since the Broncs of 92 and 93.
Firstly the WCC, admittedly this is in Australia, so will help, but it's still a big deal.
Secondly, everyone will be trying to knock them off as premiers.
Thirdly, they are not a secret anymore, every coach will be studying them (remember the Dogs tactics of 2012?? They were a revelation, in 2013 they were outdated).
Finally, all those fringe players or young player (ie Tupou, Shek, Guerra), will want more money.
I think the Roosters will be at the top end (be hard to see them not). But it's a long slog to back up a premiership.