IMO the reality is there i a lot of luck involved in winning a world cup.
look at 1995, NZ were by far the best team but they were struck down before the game and though they weren't themselves they put up a fight. my lasting memory of that game is of Jeff Wilson who I think is our greatest ever right winger going off early and vomiting on the sideline, AB's wpuld have only been about 60% that day. Or 2007 where south africa managed to get through the whole thing without facing a single team that was any sort of threat to them because of the luck of the draw and results going their way. I think their biggest threat came from fiji?.....
Argentina beat well France in the opening game of RWC 2007
England lost to South Africa 33-6 in pool stage
England beat narrowly Australia in QF
France beat narrowly NZ in QF
England outplayed France in SF1
South Africa ran over Argentina in SF2
Argentina beat again (and well) France in Bronze Final
England lost 15-6 to South Africa in the Final.
I don't see any shame here, I just see a winning team who beat anyone on his path, and a "phoenix team" who resurrected from his own ashes, thanks to key players and a winning-attitude, to become the 2nd best.
I'm sorry, but if you're saying SA's got through the whole thing without facing a single team that was any sort of threat, I dare to say you didn't see any RWC match!
Talking about rankings is, IMO, a consolation.
In between the RWC, it's a matter of 3 test in november, Six Nations or an extended Tri-Nations+Bledisloe (and some people are sick of that!) and 3 test in june, all spread in 11 month: with players rotation, turnovers, injuries and home competitions that takes the spotlight etc...
RWC is much more about attitude to perform under pressure, mind and physical as well, and to win it your team must be mentally solid and have consistence to go through 4 do-or-die matches (at least 1 pool game, +QF, SF and Final) in something less than 28 days.
And you have to do this with a group of 22-25 players (after a point, you can't continue to rotate players).
That's why people will always remember who won the last RWC, but probably they won't remember so well who topped ranking in the last four years.
Is this so easy?
Is this only matter of luck?
Now professionism is already established in this sport, I don't think so.
It's only matter of being good enough in every aspect of the game. From playing to management.