As you have probably heard about, the arena has no sound-proof booths for playing teams. Various sources have mentioned that players can receive information from English speaking casters making live comments while the game is going on, including opponent team smoke ganking, roshing, acquiring dd rune and so on.
The point about this post is that, if you are a native English speaker and don't speak a second language, you may not realize how and why this could be so unfair to non English speaking teams, and I'm offering my perspective here.
I myself speak English as a second language at work on a daily basis. I talk to co-works, attend meetings, drive discussions and lead teams, all using English as communication tool. Off-work I speak English to my English-speaking friends. I play ranked dota games in US server all the time and communicate with my team in English with no problems.
That said, when I am not in 'English mode', so to speak, it is really normal for my brain to treat English content in the background as noise, and I won't be readily receiving any meaningful information from it. On the contrary, whatever I am doing at a moment, even focused, my brain much more readily registers words in my native language. I cannot control it. It's just how my brain works.
If I imagine myself playing TI11 in an English speaking team, because we would already be communicating in English, I would say both me and my teammates should easily notice any crucial in-game information leaked from casters. If I were playing in a non English speaking team, however, I would probably still hear 'roshan', but much less likely smoke ganks, ward locations and such, while thinking and speaking in a different language. Roshan sounds like Roshan in all languages, so the brain registers, but runes, hero names and everything else can be very different.
This is from someone who has lived in the US for almost a decade, primarily speaking English on a daily basis. I imagine most non-English speaking players are less used to speaking English than myself, so more disadvantage for them. Hopefully this helps.
Source: https://www.reddit.com/r/DotA2/comments/y97d3a/a_nonnative_english_speakers_perspective_on_the/