Sledging in Australia Cricket - is it necessary?

I read an interesting editorial today in The Courier Mail by Robert Craddock where he criticised the Australian Cricket team for writing a pledge - the Spirit of Cricket pledge. The pledge is basically a commitment to values and behaviour by which the team members commit to adhering - both on the field and off. The team were reported to have had a meeting yesterday to re-inforce the pledge, in light of recent damaging reports on their sledging and other alledged displays of poor sportsmanship.
Robert Craddock implied that there was no room in sport for being nice. That the success of the Australian team is based on being 'hard-edged, sharp-tongued, no-nonsense.....who do what they have to do to win.' Robert went on to cite other known sporting team that are similarly not known for 'being nice'.
My issue with the article is that Robert perpetuates the myth that you have to be a certain charachteristic to be a winner. That's like saying you have to have the ruthlessness of Donald Trump to be rich. This is the basis of limiting beliefs that can stop a person being truly successful, if they buy into the myth. "I don't WANT to be nasty or ruthless, and therefore, I don't want to be successful."
What if you start looking at ALL the winning teams and individuals that ARE NICE also. That can win consistently and do it professionally and with respect for their opposition.
Sure you need to have a determination to WIN, and to do whatever it takes to win, but I don't regard sledging and poor sportsmanship, as a necessary formula to winning.