Football changes every single season, be it from a financial perspective, a rules perspective or, increasingly, a positional perspective.
The goalkeeper—soccer's unsung hero, the man who does the job so you don't have to—is undergoing borderline surgical change in his tendencies and responsibilities.
Adjustment is not new to the goalkeeping breed, and you can plot several points in history where the man between the sticks has had his experience altered.
There was a period when goalkeepers could pick up intentional backpasses from their own players, making the 'keeper a safe, go-to guy in the face of pressure. But that rule was abolished in 1992 due to excessive time-wasting and an overly cautious 1990 FIFA World Cup.
There was also a time in which a goalkeeper would rarely finish a 90-minute game without blood pouring from some sort of head wound, but now referees tend to overcorrect and, subsequently, overprotect the man with the gloves.
Radical change is seen elsewhere on the pitch too, with midfielders taking on a more encompassing, box-to-box roles, the classic No. 10 role all but fizzling out and wingers playing on opposite sides.
Change is a necessary and important part of football as the sport continues to grow and adapt.
And now the goalkeeping role has changed again, and it's arguably the biggest change yet.
No two clubs in world football epitomise the rise of the more versatile, mobile 'keeper better than Aston Villa and Tottenham Hotspur.
In North London with Spurs, Brad Friedel was happily minding the sticks under Harry Redknapp for a side chasing UEFA Champions League football—until the arrival of current manager Andre Villas-Boas. In combination with Daniel Levy, AVB sought to revolutionise the side by making it younger, more modern and more versatile.
Steven Caulker represented the new mould of ball-playing central defender; Jan Vertonghen came in under the same pretence; Hugo Lloris was brought in for £8 million as a sweeper keeper.
Lloris, a former Lyon star and captain of the French national team, bided his time and excelled in his debut against Aston Villa. He showed immense judgement in rushing out and clearing up while truly forming the last line of defence a high line needs.
His ability and willingness to come off his line, claim crosses, punch with distance and use his feet bettered Friedel's all ends up, and Lloris rightfully took his place as No. 1 at White Hart Lane by mid-November.
Over at Aston Villa, the incumbent's defiance lasted just two games.
Brad Guzan was allowed to leave the club on a free transfer over the summer, but Paul Lambert's first priority upon being installed as new manager was to retain his services.
With Shay Given in goal as the undisputed No. 1 under Alex McLeish, Guzan had found himself disenchanted and frozen out. He had been at the club since 2008 and played understudy to Friedel during his time at Villa, but he only received a handful of games in the UEFA Europa League and had been out on loan to Championship side Hull City.
But the fans knew how good he was—the 2009 Peace Cup, a preseason tournament, saw Guzan save two penalties from Juventus players Alessandro Del Piero and Vincenzo Iaquinta to lift the trophy.
Later that season, Guzan put in as good a showing as you'll see from a 'keeper to deny Sunderland single-handedly at the Stadium of Light.
Lambert knew of the former Chivas man's strengths, and Given lasted just two games before losing his job. Ever since, the American shot-stopper has been winning the hearts of Villa's crowd and seriously impressing the doubters.
Lloris and Guzan are two 'keepers that have embraced the more physical and risky side of the game, and it's paid off for them in a big, big way.
The reflex shot-stopper who stays on his line (Given) is no longer adequate, and many were shocked to see the experienced Irishman dropped. But Lambert is a modern manager, thinks in a modern way and isn't afraid to make contentious decisions.
Perhaps there's an argument to suggest the rise of the gutsy goalie—who rushes out at will to punch and maintains a very advanced starting position—has contributed to the decline of teams like Stoke City.
Aston Villa have been battered by Stoke in recent history, but Guzan's willingness to come off his line, claim crosses and, critically, relieve pressure on his defence saw them on their way to a 3-1 victory.
Just like with most other positions, a wide set of skills is now required to become the best goalkeeper in the world. A bit further from home, Bayern Munich's Manuel Neuer (pictured above) is seemingly desperate to play in midfield half the time, while Barcelona's Victor Valdes has received the "playmaking shot-stopper" label for his skills in distribution.
It's more than a trend, it's a goalkeeping revolution. Hop on board or get stuck on the bench!