This will probably sound ridiculous, but I can't get over the fact that he was playing Dota 2 for years, thousands of games played and was still in bronze league. I consider RTS games like this a proxy for intelligence, and while it isn't a perfect proxy due to it also requiring hand dexterity / mechanical skill / some arbitrary memorization, I do still think it's a good indicator that there was something off with him mentally.

You should passively improve with the amount of games he had under his belt, even if you put no conscious thought into why it is that you're losing or what you could be doing better. He performed at a level which is what, the lowest 10% or 20% of players? Many of whom were probably new to the game because most people will climb in rank over time.