The semi-finals of the 2010 European Cup were a blessing for nostalgics. They gave us a rarity, in the era of the Champions League: a quartet of clubs each from different countries. If you looked hard enough for the right shade of pink for your rose-tinted spectacles, its combination of French, Spanish, German and Italian teams — all of them from cities that were not national capitals — could appear romantic. And, for the first time in the seven years since Roman Abramovich had declared so emphatically that England's football represented the place to put your hard disposable currency, the competition reached its penultimate stage without a team from the English Premier League.

From across the channel that looked like a throwback. But it was what happened in the days immediately before the matches between Italy's Internazionale and Spain's Barcelona, between Germany's Bayern Munich and France's Olympique Lyonnais that plunged the European Cup properly, practically and urgently back to its exotic age. Across great swathes of northern and central Europe, thanks to Eyjafjallajokull, a bellicose Icelandic volcanic, there were no functioning aeroplanes, no open airports. Unusually, the visiting squads in the first legs of the semi-finals would not reach their destinations by shuttle; their journeys would be presented as odysseys, millionaire footballers cast as resourceful backpackers. Suddenly, the major city of Lombardy stretched 10 hours journey and two frontiers (four if you include Monaco's borders) away from the headquarters of Catalonia; Lyon's voyage from the Rhone Valley to Bavaria meant a trip of more than 600 miles, unless you were prepared to ski parts of it.

Neither of the away teams did well. Barcelona, after their unexpected, extended bus journey through the Costa Brava, via Provence and the Côte D'Azur duly lost to Inter, one of only three defeats Barca suffered in the principal competitions they contested — La Liga and the Champions League — in all of 2010. Bayern, hosting the French champions, also won at home against their road-weary visitors. By the time of the second legs, Munich-to-Lyon and Milan-to-Barcelona had become a simple commute again, Eyjafjallajokull having belched its menacing cinders.

Inter closed up at Camp Nou, lost 1-0 and went through 3-2 on aggregate. Bayern, after a short flight, made even shorter work of accumulating enough away goals in France — three — to secure their date in the final. Bayern had proved deft at scoring important away goals in the Champions League last season. They had needed away goals even to qualify for the knockout phase of the competition, hauling themselves, against the odds, to victory in Turin over Juventus to squeeze through their group on the final matchday of the group stage. Against Fiorentina in the next round, Bayern had a great deal of luck — an offside goal went unspotted — and beat the Italians on the away goals rule, a law which from now on we will refer to as the AGR. We'll stick with AGR for reasons of shorthand and because AGR looks like the kind of abbreviation that in text-message-speak might stand for 'aggravating'. Which is exactly what, at least in the European Champions League, the AGR has become. It is outdated and it stifles entertainment.

In 2010, Bayern really put the aggro into AGR. When they met Manchester United in their Champions League quarter-final, they held the lead for a total of one minute of the two 90-minute contests, while United led for a total of 161 minutes. And Bayern went through on the AGR. "Typical Germans," muttered Sir Alex Ferguson, United's manager, about certain aspects of those games. The AGR is indeed a typically German way of eliminating United from the Champions League. Twice in the last ten years Ferguson's team have lost on the AGR in Europe: Bayer Leverkusen inflicted the first.

With the Bavarians, and with Munich, United share a longer, more complex history in the European Cup. Here, it is worth remembering one of the most poignant parts of it. United's fabled 1958 team were en route via Munich when several of them perished in an air accident. The Bavarian capital was a stopover from a trip to Yugoslavia, in the days when air travel required frequent pauses for refuelling and when flying was a great deal more complicated and dangerous than it is now.

It was partly the inconvenience of long-distance voyages that persuaded the founders of the European Cup to introduce a new rule, in the mid 1960s, that would streamline their knockout competitions and reduce the need for replays. Their novelty tie-breaker said that, in the event that a two-legged home-and-away tie finished with scores equal, the team that had scored more away goals would progress. It gave an extra carrot to the away team to attack; it rewarded sides who conquered hostility and the fatigue of travel.

The AGR was first used by Uefa in 1965, in the Cup Winners' Cup. It applied to that competition and in the Fairs Cup the following season. It entered the European Champions Cup in 1967, its first beneficiaries Benfica, whose route to the final the following year included a drawn tie with Glentoran, the first British team to be eliminated via AGR. Yes, in those days the Northern Irish champions could indeed draw with the Portuguese champions, the team of Eusébio. Evidently, it was a very different Europe then.

The AGR took hold, even if it took a while for coaches and even for referees to come to terms with this new algebra. In 1971-72, Glasgow Rangers won 3-2 and lost 3-2 against Sporting Portugal over 90 minutes in Glasgow and then in Lisbon. Rangers scored again in extra time in their second, away leg. So did Sporting. But the senior match official ordered a penalty shoot-out as the tie-breaker. Sporting won it. Rangers, incensed, appealed and were reinstated in the tournament, the Cup Winners' Cup, which they went on to win.

Europe seemed much bigger in the early 1970s. Iberia was governed by fascist dictators. There were two Germanys, West and East. With no rolling news, Blackberries nor Twitter, a plausible sit-com episode could be written based on the Likely Lads avoiding knowledge of the result of an England match for half a day. Europe's airlines were almost exclusively national carriers. Countries all had unique coins and banknotes. Speedy boarding was an oxymoron, speedy disembarkation even more so; you needed visas to cross most borders. A voyage from Belfast or Glasgow to Lisbon would have been a schlep, at least as exhausting as being hemmed in on a coach for 10 hours between Catalonia and Lombardy. And there were worse journeys than that for footballers, to behind the Iron Curtain for instance, from where western European teams would frequently return with tales that fed into anti-Communist propaganda, of pugnacious military presences at airports or in stadiums; of sparse, uncomfortable hotels, sleepless nights because of noise made by fans outside bedroom windows. Or of bad food. Evidence of weak and even corrupted referees was also more widespread at the top end of European club football — and by no means just in the red East — during the 1970s and 1980s. So when the AGR started up it recognised a fact that was hard to dispute: goals on the road were a good deal harder to come by. On average, away wins in the European Cup — then contested entirely as knockout ties — between 1967 and 1972 accounted for only 16 per cent of results.

Now they are twice as likely. Which in turn means that the AGR is, at best, only half as appropriate as when it was invented. In the Champions League group phase — in other words, even when there is no AGR incentive — around a third of results, typically, are away wins. Some of those can be explained by the odd dead rubber at the end of the six-fixture schedule, but very few. The best teams are getting better at scoring away from home, especially when they go abroad. During the 2008-09 group stage of the Champions League, 31 per cent of matches resulted in victories for the visiting side; in 2009-10 it was 35 per cent. Now compare the leading domestic leagues, the ones who provide most of the modern winners of the Champions League. In the Premier League, in Spain's Primera Division and in Italy's Serie A, the portion of results covered by away wins was very similar in 2009-10, around 24 percent in each league. That's less than one in every four games.

Tactical developments provide some explanation. Many teams travelling in Europe have over the last decade fine-tuned strategies of ambush, of one up front, of playing on the break. "Successful teams now include the ability to counter-attack in their repertoire," notes Andy Roxburgh, the technical director of Uefa, which runs the Champions League, "and that's even sides with attacking traditions like Manchester United and Real Madrid." Not that the AGR has been especially kind to either of those grandees. United lost on AGR in the semi-final in 2002 and in the quarter-final eight years later. Madrid's wretched record since 2004 — they would not breach the last 16 for six seasons after that — includes two AGR defeats, against Monaco in the last eight in 2004, and against Bayern in the last 16 of 2007.

Familiarity also plays a part in the higher modern ratio of away wins. In competitions where conditions, home and away, vary greatly — in, say, the African Champions League — away wins remain very hard to come by. Poor, or fearful, refereeing would count as a factor in Africa. So would vastly distinct standards of playing surface, or the fact that a pair of matches in two-legged tie might easily take place in different seasons: winter in Tunis is scorching summer in Cape Town. In those circumstances, the AGR clearly has an important compensatory value.

But in the European Champions League, it scarcely does. Where the European Cup of the 1960s and 1970s was exotic, with a greater range of destinations and opponents, the modern format is repetitive, cliquey. By the later stages of the competition a medium-haul trip is a freak event, and will only ever involve a Russian, Ukrainian or maybe a Turkish side and whoever they are drawn against. Only in these cases might weather conditions differ greatly from one leg to the next. As for stadiums, Uefa's guidelines on arenas and pitches get stricter and stricter, so the very environment in which home and away games are played becomes homogenised. And then there's the 'prawn sandwich' principle, as Roy Keane, the former captain of Manchester United, memorably observed. Crowds at the costlier midweek evening games tend to be quieter, more corporate — they dine on seafood canapés, according to Keane, while watching — and not just in England. At the Bernabéu in Madrid, the decibel levels increase sharply for weekend La Liga fixtures from the tepid murmur of Tuesday or Wednesday.

So with a less raucous crowd against you, and a routine air trip more than 24 hours behind you, it does seem easier to pop in the odd away goal and then defend it than it used to. Advances in satellite broadcasting have also played a part. As Arsène Wenger points out, opponents are much easier to scout now, either in person, or on the box. There is less mystery. "The away goals rule was created when teams went away, with no television, played with 10 defenders and kicked every ball into the stand," argued Wenger.

Wenger is among the growing number of thinkers in the game who believe the AGR should be abandoned in Europe's principal club tournament, not just because it addresses a phenomenon that no longer exists, but because it is damaging the spectacle. Wenger knows better than most how small the physical distances have become in the modern Champions League, not just because of jet engines, but because of the modern access arrangements to the competition. When Arsenal bow out of Europe, there's a very high chance it will have been to a team they have already played twice in the Premier League that season. Since 2004, Chelsea, Liverpool and Manchester United have each eliminated Wenger's team in the knockout stages. This sort of endogamy is inevitable with the game's wealth and talent concentrated across so few domestic leagues and clubs. Barcelona have played both Valencia and Real Madrid in Champions League semi-finals; in 2003, the AGR would be laid open to easy ridicule in the most incestuous of all-Italian meetings. In the semis that year, Milan beat Inter on the AGR. Both matches were played at the same, shared Giuseppe Meazza Stadium.

Liverpool versus Chelsea, meanwhile, was at one point turning into the Coronation Street of 21st-century Champions League, as if fixed in the TV schedule. When Rafa Benítez and José Mourinho were in charge of those teams, it became its Ken Barlow: uptight and dull. Which brings us to Wenger's beef. The AGR now discourages adventure rather than promoting it. Wenger told a Uefa coaches meeting as much in 2008 and says he heard many of his fellow elite coaches agree with him. "I believe the tactical weight of the away goal has become too important," says Wenger. "Teams get a 0-0 draw at home and they're happy. Instead of having a positive effect it has been pushed too far tactically in the modern game. It has the opposite effect than it was supposed to have at the start. It favours defending well when you play at home."

Real Madrid's director of football, Jorge Valdano, holds a similar view, although he no longer expresses it with quite the flourish that he did in 2007, while he was not employed by Madrid but rather was assuming his other persona, as a lordly, occasionally verbose, arbiter of stylistic good taste in a game he once played with distinction for Argentina. The AGR, said Valdano, promotes cagey, crabby football. "You see more and more home teams incapable of taking the initiative against well-organised opposition. Those teams then feel comfortable away because the home side is obliged to relax its cautiousness and be proactive. So the AGR favours teams who are mean with stylish football. They feed off the openness of their hosts. That, by definition, makes them bloodsuckers."

Valdano reckons dropping the AGR would dramatically improve European club football. He called for its abolition as "the first remedy against parasites": An antibiotic against anti-football.

This article appeared on Episode Forty Six of the Blizzard Podcast. You can see which other articles we have featured by searching the Podcast tag, but we'd really like you to subscribe which you can do through iTunes, Soundcloud, our RSS feed or wherever you usually get your podcasts of choice.