When five substitutes were permitted as a short-term measure following the restart, fitness levels and injury prevention were the primary concerns. Any tactical significance was secondary. But the prospect of a full season with the option of making five substitutions could change all that as forward-thinking coaches plot how to take advantage.
Speaking to one former Premier League coach, a renowned innovator, he is in no doubt as the potential significance. "It could really turn the game upside down," he tells Sky Sports.
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The conventional wisdom thus far seems to suggest the change favours the richest clubs because they are the ones with high-quality alternatives among their substitutes.
Aston Villa's John McGinn made his concerns explicit when ruing Liverpool's triple substitutions on the hour-mark in his side's 2-0 defeat to the champions-elect in July.
Jurgen Klopp turned to Jordan Henderson, Georginio Wijnaldum and Roberto Firmino to alter the course of the match. Villa also saw games against Wolves and Chelsea taken away from them by the introductions of Adama Traore and Christian Pulisic respectively.
As a result, the frustration was understandable.
"We cannot thank the guy who invented the five sub rule," McGinn told Sky Sports. "It does get tougher with that rule. It does make it a lot more difficult."
Football always resists change but we must open our mind.
But not everyone agrees the rule favours only the wealthy. "Football always resists change," Portuguese coach Jose Gomes tells Sky Sports, "but we must open our mind."
Perhaps the big winners will be those who consider the potential.
Speaking to coaches about what this rule could really mean for football, one name keeps coming up. Marcelo Bielsa might be the man to make the most of this change.
That has been evident at Leeds even since the restart. In their first home game upon football's return, Patrick Bamford was taken off at half-time against Fulham despite having scored the only goal of the first half. Bielsa has followed up by making a half-time change in every single one of Leeds' games at Elland Road since he was permitted five substitutions.
The Argentine is a staunch advocate of the pressing game. This high press can be one of the most entertaining brands of football around, but it places huge demands on the players. Not only is that an issue over the course of a long season but even within individual games.
Ralph Hasenhuttl's Southampton were arguably the most committed exponent of pressing football in the Premier League last season. They had Manchester United on the run for 20 minutes at Old Trafford in July before starting to fade and allowing spaces to open up.
But what if the use of five substitutes gave pressing teams such as Southampton more chance of maintaining their intensity for longer. Making a triple change at half-time, for example, swapping out the entire forward line, would suddenly be a viable option.
Speaking to Hasenhuttl, he describes himself as "a big fan of the five substitutes" and insists he would "not be unhappy if it stays like this" but, curiously, he is yet to make five changes.
It would be a chance for a pressing team because it is intense and if you are struggling with a lot of games it is easier to make subs earlier as well.
"It is really strange that I never used it so far," he tells Sky Sports. "When I see how often I had the opportunity and did not use it, it is really what I did not believe. But the reason that I did not use it was that I had the feeling that we have been so fit that I did not have to.
"The big question is whether you use it just to use it or does it really help you? If I think that it does not really help me in that moment then I do not do it because it is not always necessary. But definitely it would be a chance for a pressing team because it is intense and if you are struggling with a lot of games it is easier to make subs earlier as well."
If anything, that decision is more straightforward for lesser teams than it is for those at the top of the table because they are not removing some of the game's superstars. Instead, they might have interchangeable options within the squad able to bring more energy to the side.
It is an intriguing argument articulated by Edu Rubio, a Spanish coach who has worked with a number of English clubs as well as being a tutor on the UEFA Pro Licence course.
"I do understand that people will say the increase favours the richest clubs because they are the ones who have the depth and quality in their squads," Rubio tells Sky Sports.
"But even the squads that are not so rich, if the difference in quality between the starting eleven and the rest is not so big then it does not matter who you play. It can really benefit those teams because they can sustain the high press for longer."
Consider the first round of games in the Premier League following the restart and the introduction of the new rule. In West Ham's game against Wolves, the two players with the highest average speed on the pitch were Andriy Yarmolenko and Morgan Gibbs-White. In Brighton's game against Arsenal, it was Dale Stephens and Joe Willock who topped the list.
In each case, this was because they had been introduced late on. They had more energy and were tasked with running around for a short period of time. These statistics are no shock, they are completely intuitive. Players did not need to run for long so they ran more.
Other examples highlight the phenomenon from the other perspective. In Liverpool's first game, Takumi Minamino had the highest average speed. He only played the first 45 minutes against Everton. For Chelsea it was Mateo Kovacic, substituted after just 55 minutes.
As players begin to tire, the pace of a game slows or gaps open up. But imagine having half of the outfield players on the pitch still at optimum fitness. That changes the game.
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So what would stop teams adopting that approach? If there is a reluctance it might be for reasons beyond mere quality but based instead on the importance of cohesion - something that is particularly important for those teams committed to a pressing game.
"Sometimes the understanding between the main players of the press is working so well," explains Rubio, "that even if they are getting a little bit more tired and they are dropping another five or ten yards you might still want to keep those players on the pitch.
"Not having such an intense high press is not as bad as having someone on the pitch who might have to adapt to the rhythm of the game, might have to adapt to the communication skills that those three or four players already have, and it brings down the whole system.
"One of the main pillars of the high press is the communication. It is the mechanism of the team. If one player does not do it properly then the whole thing breaks.
"If one player does not go in the right manner at the right time with the right body shape and the right intensity then that is now an opportunity for the opponent to break the high press just because one player was not where he should he be when he should be."
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This is where Bielsa's attention to detail, his focus on the framework of the team rather than individual inspiration, could be crucial. Throughout his career, he has prioritised the needs of the group. He will not be afraid to change the personnel in search of greater intensity.
One recent example came in the home victory over Barnsley when Pablo Hernandez, arguably Leeds' most gifted player, was introduced at half-time but withdrawn late on.
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It is an indication Bielsa is unconcerned by the optics. A clue too, perhaps, that the control he wields at Leeds could leave him well placed to take advantage of the new rules. For Rubio, Bielsa's methodology could be more significant than the quality on the bench.
"It does not matter if those players are not the best players in the world, it only matters that they work properly," he says. "It will suit those managers who really work from Monday to Friday on their methods and their philosophy. Marcelo Bielsa is one of the best at that.
"For him, it would be a big benefit because the whole squad is drilled. All of them know what they need to do. It does not really matter too much whether he chooses one player or another because they all know what the team requires and what needs to be done."
Leeds will be up against it in the Premier League. They will not have the advantage of their superior quality that they enjoyed over much of the Championship. But, in Bielsa, perhaps they have a coach who can still tilt the balance in their favour. Five substitutions could yet turn football upside down. Who would really benefit from that is yet to be decided.