There was a time when shirts numbered 1 to 11 hung in English Premier League changing rooms before kick-off, and the kit man could feel assured of whose boots should be placed under which seat even before he knew the starting line-up.
At Old Trafford in 1992/93, it was simple. Manchester United were champions in the inaugural Premier League season, their first top-flight title in 26 years.
The bedrock of Alex Ferguson's first great United side was the defensive partnership of Steve Bruce (No 4) and Gary Pallister (No 6), both of whom started every one of the 42 league matches of a campaign, which, just to add a sense of nostalgia, took in clashes against the likes of Wimbledon, Oldham Athletic and Coventry City.
United won the title the following season, too, with Bruce and Pallister this time starting every match bar one each.
Shirt numbers evolved into squad numbers, but as the Premier League progressed through the years, the memorable sides continued to be built on a solid, consistent backline. Arsenal's Invincibles of 2003/04 had Sol Campbell and Kolo Toure who started 35 and 36 league matches, respectively.
John Terry was at the heart of Chelsea's first league title in 50 years in 2004/05 when, more often than not, he was partnered by the Portuguese Ricardo Carvalho.
In more recent times, we saw the heroics of Wes Morgan and Robert Huth when Leicester City pulled off their title shock in 2015/16. Morgan started every match, while Huth missed just three. If Morgan was not throwing himself in front of goal-bound shots, his goal-repelling partner Huth was in the way in what was a double act every bit as important as Riyad Mahrez putting goals on a plate for Jamie Vardy.
But as the current season draws to a close, where have these defensive double acts gone?
Manchester City's attacking gusto has swept them to the title, and the goalscoring exploits of Liverpool's Mohamed Salah and Tottenham Hotspur's Harry Kane have taken the headlines and plaudits.
United, meanwhile, have stuttered along to second place in the league and an FA Cup semi-final against Tottenham on Saturday. The kit man almost has as much chance of winning the lottery as guessing which of Jose Mourinho's squad will be lining up in the centre of defence.
So far this season, Mourinho has used his central defenders – Chris Smalling, Phil Jones, Eric Bailly, Marcos Rojo and Victor Lindelof – in 13 combinations across all competitions. Daley Blind is considered more of a full-back, but is versatile, while Mourinho has on occasion used more than two of these players at a time.
Part of the reason for Mourinho's rotation is down to injuries, particularly to Bailly and Jones, his first-choice pairing. And football is considered more a squad game these days, with matches more intense than 25 years ago.
Despite the constant changes, United have conceded 26 goals in 33 games, one more than City, who have the best defensive record in the league. United conceded at a similar rate when they won the title in 1992/93, letting in 38 in 42 games. So statistically, the lack of consistency at the back has not hampered Mourinho's side as much as could be have been expected.
They have been aided by having the division's best goalkeeper, David de Gea, and consistent full-back selection in Ashley Young and Antonio Valencia.
But credit must surely go to Mourinho, who has so often been the subject of criticism from his own fans, as well as the scribes, for "parking the bus" against the bigger clubs, and a lack of attacking ambition against the smaller ones, especially when compared to the swashbuckling United sides of years gone by.
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He may not have been able to field the same four players across his defence as much as he would have liked, but United have remained difficult to break down, with assistance from Nemanja Matic in front of them. And part of the reason for the success has to be the manager's own defensive diligence.
"We train, we work, we organise. The players have their individual jobs in defence or not. They know their responsibilities," he lamented in February after defeat at St James's Park against Newcastle United.
At City, injuries to Vincent Kompany and John Stones have forced the hand of Pep Guadiola, who welcomed record signing Aymeric Laporte in January and relied heavily on Nicolas Otamendi. It remains to be seen if a favourite pairing develops from those four.
Another great exponent of the defensive arts was former Arsenal manager George Graham, whose techniques entered football folklore after stories of his defenders, including Tony Adams and Steve Bould, being tied together using rope so that they would move together in a line.
For Mourinho, you have to wonder who would be tied up to who?