@engineer,
It's an interesting question.
One aunt/uncle pair in Germany studied English for years. She, the introvert, was an excellent student, could read/write English quite well, but pretty much refused to try to speak it. He, the extrovert, just started speaking it - didn't study much - never quite got it right, but never let it stop him.
Famously, at the airport in Montreal - speaking to customs and immigration "we are here for the sister of my woman". mmm yeah. She winced, and he barreled along happily.
Anecdotal, but I'd say the extrovert was a good language user, not so much a good language learner. He didn't have time to stop chatting long enough to learn.