Confused? It would not be surprising, we are talking tactics, defensive tactics, and even the people who are supposed to operate them can be left bewildered by the jargon. Ask Steve Clarke, who recently recalled Chelsea's preparation for an FA Cup tie at Bristol City. "We were playing a sweeper system as Graham Roberts was back from suspension so we spent an hour-and-a-half in the hotel the evening before working out our tactics with a Subbuteo board. It didn't work - but we would have beaten them at Subbuteo."
To some it is all gobbledegook, football is about players, their heart and their art. It may have been once, but in the modern game organisation is required as well, especially in defence. This morning's crucial match between Liverpool and Manchester United illustrates the development of defensive strategy.
English defences used to be cast in the same mould. Two hard-as-nails full-backs who put their wingers in the gravel track with the first tackle, a beef-eating stopper who battered the centre-forward, and his Brylcreemed sidekick, almost as big, almost as nasty, but more mobile.
No longer - because foreign habits have intruded. While Alex Ferguson's Manchester United play four at the back, Liverpool have gone Continental with three in the centre and wing-backs making up a five when under pressure.
Not that either are totally convinced. Ferguson tried playing five, with a view to Europe, in the pre-season build-up two years ago. They trotted out for the opening game against Aston Villa and were 3-0 down by the interval. They reverted to four and have stuck to it ever since. Evans, meanwhile, having invested so much faith in playing with wing-backs at Liverpool, is now reconsidering in the aftermath of the Paris St-Germain debacle.
There are other waverers. In recent weeks, both Ruud Gullit's Chelsea and Martin O'Neill's Leicester City have changed from their customary five to a four to deal with special problems. Gullit wanted defensive strength and width to combat Wimbledon's power and mobility in last week's FA Cup semi-final, O'Neill wanted a base from which Pontus Kamark could man-mark Juninho in the Coca-Cola Cup final.
Both changes worked, but Evans is unlikely to make such a fundamental switch today. The summer is the time for that, as Arsene Wenger, a fan of the four, decided when he arrived at Highbury in mid-season. But who is right?
In theory playing three/five provides the flexibility to win the numbers game in midfield, the key area of modern football. Ideally one of the central three has the ball skills to step into midfield, with or without the ball, while his partners mark. Those players need to be capable of playing in the centre where reading the game and aerial strength are paramount, and on the flanks where mobility and quick-footedness are needed.
This is one reason why United prefer a four, their central defenders, David May and Gary Pallister, are uncomfortable in wide areas, as Pallister showed when playing for England in Norway and May in his unhappy period at right-back. If United changed systems, one of them would have to be left out. A problem with this system for English teams is that there are very few genuine sweepers. Mark Wright and Dominic Matteo have done a reasonable job of it at Liverpool, but neither are in the Matthias Sammer class.
The wing-backs provide width in midfield when going forward and protection on the flanks when defending. They need to be athletic, adept at going forward but also defensively aware. Dan Petrescu is the best example in the Premiership, David Ginola probably the worst due to his defensive inadequacies and positional indiscipline. Liverpool have Stig Inge Bjornebye, a defender, and, usually, Jason McAteer, an attacking midfielder, on the flanks. Both are athletic and good crossers.
Liverpool are generally sound defensively, their recent lapses are down to poor concentration and David James' handling errors. Their problem is going forward, but that may stem from the back.
Wenger believes the system delays a passing team, as Arsenal are becoming and Liverpool are, when attacking. "The problem is you defend deeper," he said, "and though you have more security in the centre you are less dangerous offensively on the wings.
"I would like to attack and defend in a higher position. When you defend deep it is a problem because you need five, six, eight passes on the way to goal and that is a long way to go, especially on a narrow pitch like Highbury. If a team defends well, you sometimes need to find a way in the air instead. We might go to a four next year."
The four is not really a four, it is an eight as the midfield are interlinked. The central midfielders, in United's case Roy Keane and Nicky Butt, protect Pallister and May, while the wide men cover the full-backs - it was said Sammy Lee extended Phil Neal's career at Liverpool by five years.
United's wide men, David Beckham and Ryan Giggs, though attacking by nature, are expected to do their share of graft - witness Gary Neville bawling out Beckham in Dortmund after he let Jorg Heinrich go past him on the overlap to create a chance for Andy Moller.
The irony is that English teams, like Liverpool, Chelsea, Aston Villa and the national team, have adopted a three/five just as many foreign clubs have turned to 4-4-2. Milan, Juventus, and now even the Netherlands, play that way. Germany, however, have a three/five.
Perhaps it is down to the players. Wenger again: "There is no perfect system. The best system is the one suited to the players you have. That is why some managers could be wrong in picking the system first - that can be done if you create your own team but when you arrive somewhere you have to adapt to the players.
"The right system is the one in which everybody in the team feels he can express his qualities."
ROY EVANS' CONTINENTAL APPROACH: WING-BACKS AND THREE CENTRE-BACKS
Many and varied. Stig Inge Bjornebye is the left wing-back and, until Wednesday, when he was replaced by Rob Jones, Jason McAteer was on the right. Mark Wright and Bjorn Tore Kvarme are regulars in the centre with Dominic Matteo, Steve Harkness, Phil Babb and Neil Ruddock competing for the third spot.
Width going forward, good support for midfield, strong in defensive centre.
Vulnerable on the flanks, needs athletic wing backs, temptation to defend too deep.
Good since Jones' return as McAteer would struggle defensively as a conventional full-back. Harkness can play on the flanks while the other central defenders all have experience of playing in a four.
ALEX FERGUSON'S TRADITIONAL LOOK: THE FLAT BACK-FOUR
Gary Neville, David May, Gary Pallister and Denis Irwin are the first- choice quartet. Ronnie Johnsen, who will come in today if May's injury has not recovered, is the long-term replacement for Pallister and Phil Neville is being groomed to succeed Irwin.
Provides good cover across the field with a clear demarcation of responsibility. Presses the opposition, good for offsides.
Needs protective midfield, can be caught square, vulnerable to ball over the top.
Limited. The Nevilles could play anywhere in either system but Pallister and May are much happier in a four.