Winning an All-Ireland of whatever quality carves out a specific identity for a team. People will discuss the team and define its strengths. It may be compared with its predecessors and even graded according to its perceived merits. Losers, on the other hand, are lumped in together. Limerick's hurling manager Tom Ryan was irritated at the team being compared with the Dublin footballers - for no other reason than that both had lost two All-Ireland finals.

If a team loses one All-Ireland, it's comforting to talk about "losing one to win one" and "learning from the experience". Lose two and you're clinging to the cliched wreckage. Precedent tells us that of the last 20 All-Irelands, only three have been won by the previous year's runners-up.

Mayo on Sunday face a critical test. Having lost in last year's final gives them certain advantages in experience, but the demons of negative experience can be hard to exorcise. Some teams just become good at losing.

The two most afflicted teams of the last 25 years were Galway in the early 1970s and Dublin of recent memory. Both reached three All-Ireland finals in four years - with the crucial distinction that Dublin won on their third attempt.

Tommy Joe Gilmore played centre back on all three losing Galway teams. He thinks that losing has a limited shelf-life as an instrument of learning.

"I think that Mayo's contesting two finals in one year was a useful learning experience and is an advantage this year. If Mayo are beaten on Sunday, doubt will set in for a third year and there's nothing worse than when doubt sets in."

The theory of the "learning experience" can be debunked. Before the 1991 All-Ireland final which Down contested for the first time in 23 years, the team manager Peter McGrath asked the players which was the easier way to win an All-Ireland: go out the following June and play Armagh in Armagh, then face Derry or Tyrone, next Donegal, followed by the Connacht champions and finally whoever came out of Munster or Leinster - win all those or win this one match coming up?

One of the aspects of Dublin's defeats that appeared so damning at the time was that the team lost every year to a different county. It was as if any form team would beat them. Former Dublin manager Pat O'Neill details the slow, torturous process through which the team acquired the incremental know-how to land an All-Ireland.

"In retrospect they did help the team, although not all the individuals involved. The irony is that when we eventually won, it was after the worst final of them all and the one in which we played worst."

According to O'Neill, there were specific lessons in each unfortunate setback: attitude, physical conditioning and tactical acumen.

"The lesson of 1992 was obvious, a complete loss of focus as to what the main issue is in the leadup to a match like that: the 70 minutes play between 3.30 and 10 to five. We failed to focus objectively.

"Maybe there was complacency. It was hard to avoid after the Donegal-Mayo semi-final but that was another lesson learned, that you can't go in with that attitude. From our point of view, the whole experience was also new to several players."

If the lesson of that year was that All-Irelands have to be taken seriously, the team would obviously require a lot of instruction.

Tom Carr captained Dublin that year and said some months later that the team went around convincing themselves that Donegal would be a serious threat.

Feeling obliged to convince yourself that All-Ireland finalists constitute a serious threat indicates how scattered Dublin's mental approach to the match had been. A year later, there was another defeat, this time in a semifinal against Derry.

"I don't know where the 1993 semi-final was lost," says O'Neill. "The shape went out of it in the last 10 minutes and whereas there were questions about our fitness, I believe that we had gone over the top in physical preparation and were over-trained. Trying to programme fitness properly was another lesson learned."

Having learned that mental concentration and physical fitness had to be fine-tuned, O'Neill discovered in the team's second final, against Down in 1994, that tactics can also derail a team.

"In 1994, again there was an individual distraction, the naming of Paul Curran at corner back (to mark 1994 Footballer of the Year Mickey Linden) because of an injury problem. This ended up as another learning lesson. I wouldn't do it again because you're removing a dominant player from his optimum role and you end up weakened in two positions.

"At the time it seemed a good ploy but the day was wet and the first couple of contests went - a bit unluckily - against Paul. They might have gone the other way but when they didn't, the Hill got agitated and a little bit nervousness spread around the team.

"Another problem was that we had a lot of midfielders strung across the half-forward which meant too many ball-winners who couldn't take scores.

"I am a bit sceptical about the psychological aspect because it was essentially the same team, the same personnel which won the All-Ireland a year later. There were bigger problems."

Applying all this theory to Mayo, O'Neill defers slightly to the psychological interpretation of defeat when analysing last year's final and replay.

"There was a confidence factor but there were also tactical mistakes - no more than ourselves. The major reason Mayo lost was to do with the first day. Instead of using substitute forwards, they should have seen that possession in the middle was what was required, that Pat Fallon should have been introduced."

Finally, O'Neill concurs with the view that the pressure is on the Connacht team to win this Sunday.

"There has to be a major worry for Mayo that they will end up like Kildare who are one of the best football teams - the best football this summer was played by Kildare - but can't actually win matches."