It’s become the fashion, whenever we’re confronted by an extraordinary sporting moment or talent, to grant it the title of ‘best ever’.

Almost yearly, it seems, we are told a player or team or match is the greatest in history, unparalleled, unique.

This summer the trend has been especially prevalent, with both the Spanish football team and Roger Federer being garlanded with praise for their supposed mastery over all that’s gone before.

Predictably, in an age where technology and the media is ever more obsessed with views, opinions and the vital importance of Having Your Say, both claims have been debated hotly.

For some, to suggest Brazil 1970 (or 1982, 1958, 1962…), Bjorn Borg, Pete Sampras or Rod Laver are surpassable is akin to sacrilege.

Sun-drenched images of the Azteca Stadium, the cold statistical evidence of two grand slams, Dan Maskell’s gasps of ‘Oh, I say!’. These have become articles of faith, defining not just greatness but peerlessness. These are the best there is, was and ever will be. End of story.

Others, less intractable, see an essential futility at the heart of the argument. The question for them is not whether Federer or Spain stand alone at the summit of history, but whether such comparisons can ever truly be made.

Would Spain 2012 be skilful enough, smart enough, protective enough of the ball to keep a great Brazil side in check?

It’s almost impossible to say with any certainty, though that doesn’t stop it being fun to try.

What we can establish is the impact greatness has on the rest of the sporting scene, whether an individual or team’s conspicuous brilliance sets off ripples in a wider pond.

To understand Federer and his importance requires more than just an grasp of the finer points of his technique or a familiarity with the roll call of titles to his name.

No, to truly appreciate Federer’s impact on his sport we must cast our minds back to the moribund state of men’s tennis in the late 1990s.

With both Sampras and Andre Agassi closing in on retirement, there was a sense of panic about what the future might hold.

While both great players, neither had had a positive impact on the manner in which the wider game was played, perceived and talked about.

Sampras, over-simplistically seen as reliant on his stinging serve (hence the ‘Pistol Pete’ moniker) and uncomfortable on clay courts, had unwittingly ushered in an era when tennis magazines were obsessed with recording world record service speeds, when lumbering giants with rudimentary ground strokes were being lined up as pretenders to the throne.

Agassi, a freakishly tenacious competitor, was dismissed as an uncopiable one-off. A Brazil, if you will. Sports writers genuinely worried for the future of the men’s game, unconvinced spectators and advertisers would embrace what seemed an inevitable takeover by ever-bigger hitters.

Like today’s heavyweight boxing scene, a fractured sport would be carved up piecemeal between limited athletes. Breathtaking rallies would be a thing of the past, technique giving way to brute force as tennis fans around the world switched off.

That this never came to pass is down in large part to Federer. His arrival at the top table pointed the way to a brighter future, showing that while power and strength might be essential they could still be allied to artistry and flair.

That his first grand slam win came over Mark Philippoussis at Wimbledon was remarkably apt. For the Australian even to reach the final at SW19 armed with little more than a huge serve and determination was a reflection of the poverty of talent around at the time.

Federer, while a phenomenally quick server, offered much else besides. Touch, finesse, elegance – all were back in vogue.

The brilliance of the Swiss changed the public perception about tennis and its future. Federer has been great not only for himself and his fans but for the sport of tennis as a whole.

Limited players (Del Potro, Isner, Cilic) still make a good living from the sport but are some way behind the elite group at the top of the game.

By a similar measure, perhaps we can begin to judge Spain. Unlike many of the finest sides down the years, this team can reshape the way the game is seen, understood, discussed – and played.

Whereas the tendency with Brazil was to shrug, say ‘blimey, they’re freakishly good’ and stick Mark Hateley up front at the Maracana, Spain’s brilliance is an object lesson in the value of organisation, of placing possession at the heart of everything, of penning in opponents through relentless control of football matches.

Unlike the Brazilian model, this is replicable. It’s a variant, though perhaps a less flamboyant one, on the formula that’s made Barcelona a dominant force. Crucially it’s also been shown to work at smaller clubs of more limited means (*cough* Swansea City), suggesting that a reactive approach based on ceding command of the game to the opposition is of limited use to a team with pretensions to win consistently.

Spain, in claiming football’s greatest prizes playing this way, are reshaping their sport.  Even when they appear to labour they remain composed, doctrinaire, unshakeable in their beliefs. In fact, it’s the games when they’re not quite as perfect which underline the overall value of their approach. It gets them through.

Similarly, the 2012 Roger Federer is almost more enjoyable to watch than the flawless automaton whose perfection was bludgeoned out of him on Centre Court by Rafa Nadal in the relentless (best ever?) 2008 final.

Like a castle falling in to the sea, the brilliance occasionally giving way to glaring aberrations, Federer is compelling to watch now more than ever. The mechanics of his game are there to be studied, analysed, even improved upon. His influence may cross generations.

Are Spain the best ever? If the essence of the question is would they beat Pele’s Brazil, Cruyff’s Holland or Puskas’s Hungary, it may be unanswerable. If it’s whether their methods enrich the wider game, their legacy may be answer enough.