Kelly, who turned 28 last month, still feels the pangs of all those bad days, but this has only galvanised his spirits going into a head-to-head with Western Samoan Freddie Tuilagi, and the winger is more than determined to reverse a real catalogue of unending disappointment.
"When I think back and remember how gutted Donncha O'Callaghan felt that day -a guy who gives everything to club and plays fleetingly with Munster - it really hurt him as it did myself. All these defeats make you more determined to go out in Cardiff and win the big one. We've been going to a few finals now and came out of them the wrong way. We are really determined to win the European Cup now. Of course the club guys are very disappointed - that's the end of their season and it makes us even more determined to go and do something right in Cardiff."
It has been a real rollercoaster season for a man brought through the youth system in Cork and who was only encouraged to take the game seriously at 18 from Con mentor John O' Sullivan. His upbringing wouldn't bestereotypical of the Stringer's and O'Gara's of the Cork rugby fraternity.
Such is the hegemony of the School game in Cork and Munster, the Youth system merely peeps in from the side. Educated at St. Francis Capuchin College in Rochestown, he dabbled in hurling and football but got down to the serious stuff in the evenings with Cork Constitution. That sense of Schools versus Youth system was summed up in one incident during one particular game with Con: Kelly knocked on during a vital part of the game and then a wag shouted down from the stands that that kind of obvious error would never happen to a 'Schools' player. Incidents like that only thickened his resolve to prove them all wrong.
The hierarchy in the Cork game was obvious then. And it seemed upuntil his first cap against Italy, Kelly had to fight hard to even to get noticed. As one teammate commented: "You got the feeling in Munster that he was being ignored by the Irish selectors for far too long. He was always playing so consistently, flawless at times. But we ere all thrilled to see him get that first cap."
It's where the tag of the most underrated winger became imprinted on the Munster rugby psyche. Then again, he had more fun at that age in
"In may ways it can be a small bit harder if you are coming from the club set-up. Schools players are already in the limelight, so as a club player you really have to prove yourself. Today I don't think it is a factor. If you look at the Munster team, there are many guys there who didn't play schools: look at Alan Quinlan, John Hayes, and John O'Neill - they have all come through the Youths set-up.
" I don't think it's as much as a factor now. I think people recognise that there are good club players out there. You lose out in the Schools experience alright, you miss out in the colour and atmosphere of a Christians/ Pres games. But those players seemed to work very hard whereas I seemed to enjoy my school life. I suppose I had a bit more craic than those fellas."
Kelly has played with most representative sides and when he got his first A cap against England in 2000 (ironically at the same venue as this year), many thought that full honours would soon follow. He had to wait but against Italy this year, and for Kelly who had waited so long for this day, it was real Roy of the Rovers stuff, a fairytale beginning to a burgeoning rugby career.
"I've always dreamed of this day," Kelly's words screamed from the Sundays the following morning. He had arrived.
But John remains philosophical about the whole experience. "The day against Italy was a day I will never forget but I can't live off that either. It's always the next game," Kelly reflects. " I've had some great memories: the Newport game, beating Toulouse and scoring a try and beating Castres.
But you've got to look forward. Of course I've had good days but you've got to think of the next one as well." And with regard to being dropped in the final matches of the Six Nations against France:
"I was disappointed but I wasn't upset. I wasn't angry at anyone. At the time Shane Horgan was playing better rugby than me."
But now it's all about Munster and Kelly divulges the special spirit that is only brewed in the Munster camp; a cocktail of Galwey and Claw and other big brand names. "I think the management has a lot to do with that and guys like Mick Galwey, Peter Clohessy, Anthony Foley while in the backs you have big match players like Peter Stringer, Ronan O'Gara and Rob Henderson. They're all leaders so there's a very good focus and a very good spirit in the team. It's about being professional and trying to win all the time. We're trying to be competitive in every competition we are in and trying to achieve the best results we can in every competition. Throughout the last three years the aim has been to win things."
In the overall scheme of things, John is only to delighted to wake up in the morning and head off to rugby training, and he'll be packing his bags soon after Cardiff for the trip to New Zealand for potential head-to head with Jonah Lomu. "I couldn't be happier doing my hobby as a living. Everyday that I'm playing professional rugby, I'm going out there to try and enjoy it with Con, Munster or the Irish set-up I'm lucky to be doing it."
Nicknamed 'Rags' - for a tendency to get a tad narky during a game, but not to the point of getting his marching orders. Now he is earning the potential riches of making it to the to top of his chosen profession.