In principle, I understand the calculation system for duels and clan matches, but I don't quite understand how the rating will be calculated in Tournaments for individual players.

And also, since we're talking about unity, I think we should have regular Tournaments for all versions of the game, with a unified rating system, and their rules should be posted in a closed topic at the very top of the Tournament section.

The calculation in Tournaments takes a long time and is tedious. Everyone is ranked, a draw is made, and the results are calculated round by round, from first to last. This is the main drawback – the system was designed to be automated, but even then, you still have to enter who won against whom.
The system works and objectively reflects the strength of the players, if, of course, at least 70% of the entire rating list regularly participates in the Tournaments.
From the new year, there will be a Tournament schedule. There is a closed topic with rules for 3 heroes! But since there may be some differences in Tournaments, the rules are made closed, and the regulations are for the Tournaments. This is a little more convenient – newcomers don't need to read the rules at all, but only what applies to a specific Tournament.

Added 4 minutes later

We don't even know how many people will play in the clan Tournament for the classic 3-player game, since the Tournament is open – send the save on time, and you are a participant!

Now we will know, because the saves need to be posted on the forum! Natasha came up with a good way to make her job of sending saves easier!!!
However, even in the closed Tournament, we don't know who sent the saves, and some of the "participants" were not participants at all.