Hearing what other people have to say leads to much faster improvement, especially during arenas. In the end, teamwork matters and timing & rotating abilities/cc with each other matters too, which is always easier to do with voice coms.
You will not have it easy if you’re socially withdrawn and afraid to talk to people. Just accept that it’s going to be much harder until you get over that fear. Sometimes you have to go the extra mile to make it improve.
A tip if you’re too afraid to talk to people, the least you can do is sit and listen. Just say your microphone is broken or something random like that, if they ask you why your mic is muted. Finding someone able to call out plays tends to be harder than just taking that role yourself in my experience though. Doing it yourself opens up the possibility to let others do it when they choose to, and that way you’re guaranteed to always have someone unifying the team’s actions like that even if someone else wants to do it instead of you (most randoms I’ve played with haven’t wanted to though).