Tractor and Naft both had 57 points, but Tractor was first because of higher goal counts. Sepahan was the third team with 56 points.
In last game, Tractor was playing against Naft, if either of them won, they would be the champions, if they would finish with a draw and Sepahan won, obviously Sepahan would be the champion. If Tractor and naft would finish in a draw and Sepahan not winning, then Tractor would be champion. Tractor was 3-1 ahead until mid-second half, when one of their players was sent off by the referee, after that they received 2 goals from Naft and to end up in a 3-3 match. In last 10 minutes, strangely, tractor was not attacking and was trying to preserve ball to waste time, while in other match Sepahan was winning the game. It seems they were told by their team staff that Sepahan had a draw in the other match and that with same 3-3 result, they'd be the champions. The main culprit seems to be the son of Tractor's Portuguese coach which told his father in last minutes that Sepahan was having a draw. After the game was finished, they started celebrating (which was strange for tv reporter and everyone else), then they found out that Sepahan had won the game in the other match and that they are not champions.
After that many stupid rumors came out, with Tractor's authorities blaming that on different things, like they had lost cell phone signals or radios and even TVs in last minutes, so they didn't know about final result of Sepahan match, which is very highly unlikely. But after they understood their own faults, they didn't go on with their claims.
Whether or not referee's decision to send off Tractor's player out of game was right remains to be seen. But the blame goes directly to Tractor's players and also staff. After mid-second half, they really played bad and they received 2 goals easily. It's like they thought they are champions anyways so even a draw would not matter, but that ended up costly for them. They could easily defend their 2 goal advantage and become the champions without any doubts and without relying on referee or the result of the other match. I don't like Iran's league, only follow Barca and champions league, but I assure you no conspiracy theory is involved here. It's all football with its usual rumors.
Controversial decisions, referee and players' performance etc are always there in football matches, but nothing strange happened here, but there are always people like
@atatwolf who don't even know what has happened, yet they try to spread their own agenda.