His crime, it seems, is to have pushed the boundary of what many thought possible. Possible that is in terms of ability, longevity and commitment rather than possible in terms of bending the rules.
There was a time when achieving the near impossible was once the driving essence of sport. Roger Bannister was a hero for breaking the four-minute barrier for the mile and Nadia Comaneci had a film made about her perfect 10 at the Montreal Olympics.
Not so long ago every boundary shifter - Jack Nicklaus, Mark Spitz, Bjorn Borg, Shane Warne, Michael Jordan - was celebrated and revered for their human endeavour.
Rugby used to be like that, too. Gareth Edwards, Barry John, Phil Bennett, Colin Meads, Serge Blanco, Andy Irvine, David Campese - they were universally recognised for being the great players they were.
Perhaps it's the curse of the digital age where talent show mentality pervades and convinces anyone with a Twitter account that their opinion matters. It's cool to be a critic these days and that, to some extent, explains why no one outside of New Zealand is going to acknowledge McCaw's brilliance. That's why when McCaw pulls off an unthinkable number of turnovers and tackles in the test arena he's a cheating grub. Someone, somewhere can make a name for themselves by throwing grenades at the All Black captain.
The problem is, though, that the currency of being contrary and offensive has been diminished.
It's now a mainstream belief that he's a cheat so those in search of their 15 minutes of fame may have to try something different to be heard.
Branding McCaw a cheat is a sad, tired business and it is most likely a forlorn hope that it won't happen at the World Cup. What makes it particularly sad is that rugby is a sport that prides itself on its community values and sense of brotherhood.
It is one of the few games where players and fans from vastly different cultural and socio-economic backgrounds mix freely and easily. Barriers don't exist in rugby and it's not supposed to be a sport where small-mindedness, spite and jealousy cloud the judgement.
Not everyone has to like McCaw, but the World Cup will be a better tournament if everyone can at least agree to respect him. For a No7 to survive 15 years in test football is astonishing. World Player of the Year three times; World Cup winner; 100 tests as skipper and he's even managed, according to Graham Henry, to have played the perfect test match. Twice.
Rugby is chopping itself off at the knees with this inane pursuit of the game's highest profile figure. McCaw isn't perfect. But he's not a systematic cheat. He gets it right more than he gets it wrong.
Rugby's message is: don't be better than the competition - it will put you under suspicion. By September that has to change.