Athletic Club have their world champions back. Goalkeeper Unai Simon, defender Aymeric Laporte and winger Nico Williams have returned to the club's Lezama training complex, three weeks on from lifting the trophy with Spain in New York. All three have passed their physical testing, and the plan is for them to rejoin full team training with the rest of the squad on Tuesday.

The timing is deliberate. Players who went deep into a major international tournament are given extended vacations precisely because they finished their previous season later and under far more physical and mental load than teammates who did not travel. Three weeks off, then a controlled return with testing before they touch a full session, is how a club protects a returning international from the injury that so often follows a rushed reintegration.

This came the day after the rest of Edin Terzic's squad lost 3-1 to Marseille at the Velodrome. That result underlined why getting the internationals back matters. The friendly was not a disaster to be over-read, but Athletic conceded three and managed only one in reply, with Oihan Sancet supplying the lone goal, his fourth of a productive preseason across four different friendlies. The group that has been training all summer has looked short of its best, and the returning trio raises the ceiling considerably.

The two-speed squad problem

Here is where it becomes a US coaching problem, not just a Spanish one. Every fall, coaches face a version of the two-speed squad. Some of your players spent the summer in a demanding environment, an ODP camp, an ECNL showcase, a long club season that ran late, or a national-team age-group window. Others took the summer off, or trained lightly, or are just arriving from a different sport. You cannot treat both groups the same in the first week of preseason.

The tempting mistake is to run one session for everybody and let the fittest set the pace. That either underworks your returning stars or, more dangerously, drags your under-conditioned players into a load their bodies are not ready for, which is how you lose a kid to a hamstring or a stress injury before the season even starts. Athletic's answer, testing the returnees and staggering their entry, is exactly the model to copy at your level.

Build the runway, then merge the group

Practically, that means individualizing the first two weeks. Give your heavily loaded summer players a lighter, monitored return so they do not tip into overtraining, and give your under-prepared players a progressive ramp so they catch up without breaking down. Then merge the two streams for full-team work once everyone is in a safe range. It is more planning up front, but it is far cheaper than managing a preventable injury in September.

There is a team-culture angle too. When your standout players return late from a big summer, the group that put in the base work all preseason can quietly resent it, or conversely can lean on the returning stars to carry everything. Athletic bringing Simon, Laporte and Williams back onto the same field as the players who lost at Marseille is a chance to reset both dynamics: the stars have to earn back their rhythm in training, and the grinders get the lift of playing alongside them.

The scoreline against Marseille will be forgotten inside a week. The reintegration plan is the part worth studying. Whenever you have a two-speed group, do not paper over the gap with one blanket session. Test where each player actually is, build the under-prepared ones a runway, protect the overloaded ones from doing too much, and merge only when both groups are ready.