I think the most commendable thing about Belsa is the oppression system, especially the rotation oppression during the Chilean national team, which really makes people shine. Klopp and Guardiola both learned from him. Belsa's problem is not tactics. His tactics are very advanced, even advanced. His problem is that the tactics are too carefully arranged. Every time a player moves and passes the ball, there are requirements. This team must work very harmoniously in order to exert its tactical strength. However, players are also people. They have long been restricted in their freedom and are under high pressure. This situation will not last long, and teams with many big-name stars will not do it. Therefore, Belsa's coaching career is not long once, and most of them are not top teams.
One of the reasons for England's long pass was that the grass quality in English football field was reduced and the risk of passing the ball on the ground increased at that time. Players play football on this grass since childhood, and the quality of long pass is guaranteed. Later, when the economy recovered and they had money to mow the lawn, everyone began to practice long pass on the ground, and the quality also declined. However, the tactics are relatively backward, and many teams have not completely given up long pass. I remember Nottingham Forest and Liverpool were the champions of the Champions League at that time. Now Nottingham Forest has completely sunk, and it took Liverpool decades to recover. What a shame. It is very different from the similar formation now.
A well-defended central defender is easy to find, but a full-back with good offensive and defensive skills is hard to find. The so-called ability to play both centre-back and full-back actually requires defensive position and the ability to make up defensive positions. As long as it is not a big central defender who turns slowly, almost all central defenders can do it. However, it is too difficult for a full-back among the four defenders to find a good one. In addition to defensive awareness, he must also have offensive ability, good physical fitness and not be slow. These can all become first-class full-backs, and there are only a few people in the world. Relatively speaking, it is easier to find a lot of wingers who meet the standards of first-class leagues, and wingers don't need such good defensive awareness.
I think it would be amazing if his tactics were carried out by top players. It is difficult to find a group of top players who are willing to follow his tactics. To put it bluntly, his system does not treat players as people, but as animals. Is a fixed 3-4 people, 7 people in the frontcourt will alternately rotate to the front line, and those who retreat to the second line will get a temporary "rest", thus making the crazy oppression on the team level last for 90 minutes, so I think Belsa's tactical theory is more in line with the present and let go of certain freedom. Belsa's personality is too self-centered, and he is not good at flexibility and worldly wisdom. This is the main reason that restricts him from coaching the giants.