7 minutes arena fights?

Last few days always happened something strange with me in the arena. I tried to be the first in my server, but I could't start fight with the first 2 people they were in fight always, I started spamming them more than 7 minutes before the arena close, but nothing and thats happens alway. Its possible that they just keeping each other in fight, but when the fisr over I have small chance to start, so I am the never lucky man, or dont know... But today happened a more interesint thing, they were in fight, like every time, but 30 seconds before the close they swapped and the guy's, who was the first, team has changed, so HOW possible to be his team in fight when someone other fight with him and during change his team? His team always was the same, but when somebody beat it, its changed... I tested that when I fight with someone behind me, and I lost I wont lost my place, so Pls explain that... Or that how could I challange them