Golden Ages are admittedly more easily perceived in retrospect than at the time, but Welsh fans of the 1970s and the predecessors of the first decade of the 20th century knew they were living through special times. "Strange" rather than "special" is the adjective called to mind by the last eight Six Nations seasons.
Grand Slams are not to be sniffed at, whether won singly or multiply, but when they come in fairly rapid succession, they usually reflect a period of dominance, peaks surrounded by imposing foothills. Wales's trio are more like the volcanoes of Chile, rising spectacularly from a desert floor.
Those three five-win seasons represent the only times since the Five Nations became Six in 2000 that Wales have finished in the top half of the table. Their seasonal average for the other 10 years is 1.8 wins. This inconsistency of performance has no previous parallel in the tournament's long history.
And then there is the truly gruesome record against southern hemisphere opponents. Nobody regards the 21st century as a golden age for Scotland either, but their record of four wins in 23 matches against South Africa, Australia and New Zealand looks all-conquering beside Wales's two wins in 40. Both were over the Wallabies, who have taken copious and excruciatingly tantalising revenge over the last year and a bit with six consecutive victories by an average margin of 3.67 points.
Some argue that Wales dislike being favourites, and so fail to live up to expectation in the years after they have triumphed. Yet there is little evidence to support this. Over the past 25 years, Wales have rarely been favourites for anything, least of all against the southern trio. That the three teams who did get into a position to win something all followed through to the extent of a Grand Slam rather argues the opposite.
And, of course, we don't yet know that the triumphs of 2012 will not be followed by a fresh wave of Six Nations victories in 2013, starting with the visit of Ireland to the Millennium Stadium on Saturday. But the portents are not good.
An autumn international season which began with talk of sealing a top seeding at the next World Cup ended with four home defeats and ignominious descent into the third rank. Welsh Heineken Cup results were their worst in the competition's 17 year history. Head coach Warren Gatland is off on Lions duty. His stand-in Robert Howley has limited head coach experience and grim statistics from days when he has deputised for Gatland.
If there is a single proposition on which every international coach agrees, it is that top-class rugby is a game of narrow margins. On the right side of that delicate balance in the 2012 Six Nations, Wales have slipped on to the other side.
There are reasons recognisable to any nation which operates on comparatively limited playing resources. Injuries strike, taking out prop Adam James and flanker Dan Lydiate, the two least dispensable players, for the autumn programme, followed by the four best locks and the likeliest contingency convert to the position in advance of the Six Nations. Half-back would be a real worry even if everyone was fit.
Where new talent presents itself, it is in positions already well covered. Wing Eli Walker must compete with the established George North and Luke Cuthbert. Justin Tipuric may be the best open side in Britain on current form, but is hardly going to displace incumbent skipper Sam Warburton.
And, while beneficial to individual bank accounts, the departure of several players to France has hardly helped. When even France's coach complains about difficulties with player release, countries operating to different training timetables are seriously disadvantaged. There are also dark mutterings about the lower tempo and fitness demands of the Pro 14.
But not everything is a reason to be cheerless. This is after all a group of players who have proved that they respond positively to having points as well as pride at stake. Adam Jones is back in action, with Lydiate hopefully not far behind.
Much depends on that opening match. If Wales maintain their recent edge over the Irish, the three consecutive away matches which follow – starting with the ever-forbidding trip to Paris – will look that much less of a Calvary.
Wales last completed consecutive Grand Slams in 1909, and no country has accomplished it in the Six Nation era. Even allowing for the weird unpredictability of modern Welsh performances, this does not look the team to break those sequences. But a top half placing may not be too much to ask.