Def incorrect. The head coach had an appt that day. He gave the asst coach tips on how to look after the kids since he would not be available that day.
The team itself has numerous (mostly?) stateless kids - refugees from Myanmar and elsewhere.
About each person in the cave
https://www.bbc.com/news/world-asia-44762010
Articles discussing the asst coach
http://www.asianews.it/news-en/Waiting-anxiously-for-the-boys-trapped-in-the-cave-44295.html