When a team loses possession of the ball, they need to get it back. But they cannot press the opponent team all over the field as it would tire them out way before the opponent team lose the ball or get tired.
Therefore, they have to let the other team come to them. When the ball is far away from their goal, they let the other team work on the ball at a leisurely pace. Only when the ball gets into the striking range towards their goal, they become serious about dispossessing the other team.
Previously when I noticed such behaviour, I always thought of such teams as lazy. Even when the Thai team won the final of SEA games football this way, I still regarded them a bit "lazy" or conservative.
But a few days later, I read a fabulous book, "Soccer Speed" by By Richard Bate and Ian Jeffreys. They sanction such deep defending as a good way to conserve energy.
This is reminiscent of Sun Tzu, Chapter 6:
17. For should the enemy strengthen his van, he will weaken his rear; should he strengthen his rear, he will weaken his van; should he strengthen his left, he will weaken his right; should he strengthen his right, he will weaken his left. If he sends reinforcements everywhere, he will everywhere be weak.
Therefore, at essaykkn we take special care not teach everything to our students. First, we kill 1 or 2 fatal mistakes. Then we pounce on areas where rewards are highest per effort.