In both worlds, he felt the macho pressure to be one of the boys, whereby proving one's stature comes with how much booze can be downed in a single sitting.
And then another sitting. And another.
He was handed his first Super Rugby appointment in 1997 and the Argentina vs France test in Buenos Aires the following year. By 2009 Walsh was pre-eminent in the code as a top whistleblower. But with pre-eminence comes revulsion in certain circles and Walsh was feeling it.
Despite subsequent events, Wellington fans simply don't have it in them to forgive him for their unsuccessful 2001 Ranfurly Shield challenge at Jade Stadium.
In their best chance for two decades, Wellington watched a 29-12 lead evaporate into a 31-29 loss when Ben Blair scored for Canterbury in injury time.
Grief-stricken, there was only one place to point the finger. Walsh had whistled up a 21-4 penalty count against them, plus sinbinned first five-eighth David Holwell and replacement midfielder Jason O'Halloran.
Canterbury captain Todd Blackadder called for peace. O'Halloran said he wouldn't cross the road to talk to Walsh again.
"The less I see of him the better. It was a joke. Everybody recognised he went out there to referee only one team."
Even when Walsh held the reins again in 2008, when Wellington finally ended their 26-year shield hoodoo by thumping Auckland 27-0, there was no sense of appeasement.
And that was just at domestic level - go ask an English rugby supporter for his two cents on the man from North Harbour.
By December of 2008, the NZRFU knew they had a problem that could no longer be ignored.
Walsh arrived on the morning of a Sanzar officials conference in Sydney after a night out drinking until dawn - his boss took one look at him and asked him to leave, before making a formal complaint.
It wasn't an isolated incident, the country's top young official was staying up after every game and drinking to the point of blackout as a "release" from stress and depression, before following up with another binge midweek.
Counselling hadn't helped, his weight ballooned and he wasn't training - and by April of 2009 the NZRFU announced Walsh was "retired".
Searching for redemption and knowing he could not stay in his current environment, Walsh packed a bag and left under a considerably dark cloud.
What followed is a good example of rebuilding from the ground up, if his fellow countrymen would be willing to judge it so.
In Sydney, he worked as a labourer and a courier driver to pay his way while refereeing in the local club football scene.
By 2010, the ARU was willing to give him a chance at Super Rugby again, and a year later Walsh became his adopted country's only selection for the 2011 World Cup.
Looking back, Walsh doesn't want to preach, but says he always felt New Zealand has had a troubled relationship with alcohol, and admits if he pointed the finger at the culture he would point two back at himself.
"I know I feel better about myself today than I have in the past, but I still realise I'm an alcoholic and I do delude myself sometimes and think about the few occasions I was a 'good drunk' instead of the fact that, most of the time, I used to wake up feeling shame because of my actions the night before.
"Most New Zealanders drink to get drunk - and we get aggressive. We're a little immature."
By accounts, he hasn't touched a drop since 2009. In Sydney, he hits the beaches, rides bikes, visits the morning markets and is more comfortable in a cafe than a bar.
He has never pretended that certain circles back home will scoff at this tranquil existence after he blotted his copybook here - as if there is no price too high for him to pay.
"I don't really see myself going back to New Zealand. Never say never [but] I feel freer over here, rightly or wrongly.
"When you're in Australia or in Sydney, rugby is the fourth code and fourth sport, and I just don't feel the eyes on me, so you can get on with being yourself.
"I've made some big life changes and I've never been happier."
After that game in 2001, Walsh said he had "made peace" with his performance and his competency within the game.
It appears that 14 years later, he finally means it.
