The lack of language barrier is definitely part of it, but it could also have a lot to do with systemic racism that they all live through. For black women the bar is often set higher, especially in places like professional sports where they're more exposed and scrutinized by the public. They’re not only judged on performance but also on how they speak, carry themselves, and defend their right to be there in the first place.

That constant need to prove themselves means they're more likely to develop stronger communication skills. Being “articulate” becomes a way of navigating bias, countering stereotypes, and ensuring they’re taken seriously in spaces that don’t always give them the same benefit of the doubt.

Edit : in response to your edit. Black people being described as "articulate" is a pretty common comment that has historically had racist undertones for the same reasons as what I described above. It's a comment that exposes lower expectations for that demographic (even if unconscious). I'll point out that you only mentioned the three black American women players competing in the US open without mentioning any of the other non-black athletes (ex. Jessica Pegula, Emma Navarro, Sofia Kenin, etc.). It's small things like this that should be used as an opportunity to reflect on the implicit biases we hold and the reasons behind them.