Beyond the numerous connections to players who’ve come through MLS NEXT Pro en route to their FIFA World Cup 2026 selections, the league also helped shape the quality of competition itself in the summer spectacle.
Innovation is at the heart of the league’s founding pillars, making it intentionally structured for experimentation.
Since the inaugural season in 2022, work began on improving the evergreen pace of play topic in the global soccer community, playing out with the off-field treatment and timed substitution rules, which were officially deemed World Cup-ready when adopted into the International Football Association Board's (IFAB) Laws of the Game in February.
"From the start, the results were very positive. We felt really good about them," said MLS NEXT Pro President Ali Curtis. "But it's super important that they're tested in meaningful matches at a high level, where stress is important, and the more stress you can put underneath these rules and understand the different nuances of them, the more confident you feel about implementing them at the highest level.
"And so it's great that they're in MLS, they were tested also in Leagues Cup as well, and now they're full-time, and I can't wait to see them in the World Cup."
Here’s a closer look at how that came to be.
What are the new rules?
The off-field treatment rule enforces a 15-second time limit where a player with a suspected injury must return to play if able. If the player remains on the ground beyond the time limit, the referee will stop play, allow the player to be assessed by medical staff, and be removed from the field. The player will be removed from the field for a minimum of two minutes and receive further treatment and return when safe. In the World Cup, that holding period will be one minute.
Exceptions to the off-field treatment rule include potential head injuries, goalkeeper injuries, serious medical events, and carded fouls.
The timed substitution rule means players who are being substituted out of a match must leave the field within 10 seconds. If this 10-second window is violated, the incoming player must wait through a 60-second holding period and enter the match during the next stoppage. While in the holding period, the substitute's team will be down a player.
Exceptions to the timed substitution rule include injury and goalkeeper substitutions.
Why they work
After successful implementation in the first two MLS NEXT Pro seasons, both rules were adopted in MLS and Leagues Cup in 2024 and showed they were scalable at the senior level.
Off-field treatment resulted in injury-related stoppages being reduced by 72%, marking a drop from an average of 5-6 instances per match to an average of less than two.
"Originally, the off-field treatment rule was to try to alleviate the amount of time that was lost," explained Mark Geiger, general manager of PRO Referees. "Especially towards the end of the game, when a team may have been winning, an away team was winning by one goal, it was a tie game, or even a championship match, you had players that were going down with cramps or other minor injuries instead of playing and letting the game flow as much as possible."
In addition to reducing stoppages, the rule came as a supplemental aid to ensure treatment is provided to players when needed in those high-leverage moments.
"There is a very strong case around player health and safety as well," Geiger continued. "Because when you have a player that's off the field temporarily to have treatment for a particular injury, there might be pressure that's put onto the medical team as well to get them back out as quickly as possible...it really gave the medical staff the amount of time needed to give proper treatment to the player, so that they were ready and fit to go back out onto the pitch."
As for the timed substitution rule, 99% of subs were completed in 10 seconds or less in MLS in 2025, with only 12 violations across over 4,000 substitutions.
"It's cut back a ton," said PRO referee Jeremy Scheer. "We've seen sometimes doing three to five subs at a time, and how that's taken out a ton of extra time that we've had to deal with in the past. Because they all know when the board goes up, they can see their number, and they run off the field because they know they don't want to play down any amount of men for any amount of time.
“We've seen a dramatic decrease in the time wasted when it comes to the substitutions.”
Scheer, having officiated the very first MLS NEXT Pro match in 2022, has been instrumental in implementing both rules.
"It was simply implemented, players bought into it really quickly," Scheer continued. "And it was something that the entire league was able to understand, and really, you saw buy-in from everybody...and we really didn't see much pushback."
The collective buy-in from players, coaches, and officials made way for clear data that helped prove the rules were ready to be tested on a bigger stage.
"MLS NEXT Pro has been a really good proving ground for a lot of these training or a lot of these new rules that they're bringing into effect," Geiger added. "The players in the competition have been very open to trying out new things, and look, not everything is going to work, not everything is going to be something that we can implement on the on the senior team level or in Major League soccer, but we've seen some really, really good developments, and a lot of the things that have been trialed in that competition have been elevated to MLS, and now we're seeing elevated to the FIFA level as well."
The world was watching
Brick by brick, and in collaboration with personnel from all corners of the MLS ecosystem, the rules and their results became a topic that would be addressed at the IFAB general annual meeting in Hensol, Wales.
"Change is very hard, particularly for those in our sport," Curtis admitted. "But, our north star has always been to do things for the good of the sport and good of the game, and we felt that introducing these new rules would be good for the game."
IFAB voted to adopt both into the Laws of the Game on February 28, giving everyone involved runway to be ready for the 2026 World Cup.
