Question about the ranking system because my son is going crazy

Hey guys, I have a question. As an old competitive CS player. Nowadays I play less but enjoy watching my son stream to the tv as he play Valorant and he has become really good at it. But how the actual F does this ranking system work?! No matter how good he plays he cannot get up from bronze because his teammates looks like bots. Last game he lost 11 to 13 and my cup spilled over and that's why I'm here. He did 2 ACE, ended up at 460 score and 38 kills. When he wins he get like 12-15 rating, then if he cannot carry hard enough he loses like 30 sometimes. I get frustrated as hell watching it, and you can imagine his defeat. He averages like 25 kills per match but eventually the teams get so bad it becomes a losing streak no matter how good he plays.

I love to watch him play and see how he gets better and better, sideline coaching him there. But it cannot be the case that if you cannot carry the entire team you lose 9/10 times.