Success in one area typically correlates with success in many other areas as well. Otherwise we wouldn't have polymaths. There are people who are among the best in the world in fields that are completely independent.
This is especially true if the new area is something they're peripherally familiar through everyday experience. I'm a teacher, so teaching comes to mind, here. Everyone has opinions about teaching and learning because everyone spent 15-20 years of their life doing it.
Intelligent people often act as if
Understanding of Area A + Familiarity with Area B = Understanding of Area B
See also: every thread ever on HN about law, politics, race, or gender.
In my experience, one's ability to develop expertise in many fields has much more to do with one's temperament. Most people I've met who who are able to do this live in a kind of visceral, mortal fear that they might believe something that isn't true. They're more likely to see certainty (in others as well as themselves) as a symptom of utter, hopeless confusion than as a symptom of understanding.
Blah blah anecdotes, yadda yadda caveats.
Consider the recent story about how Elon Musk (arguably the most brilliant polymath of our era) chewed out an employee for missing a work function attend the birth of his child. That's appallingly stupid. That's pure blindness to instinct, cultural values, and compassion. There you go. Elon Musk, fscking idiot.
More generally, a lot of people with brilliant technical skills have lousy social skills - social failings that can drag a team's effectiveness down as much as a technical idiot can.
A brilliant engineer can have an amazing, world-changing technical career without ever realizing that he'd be 10x more effective with better social and leadership skills. Whether one sees that truth about themselves has much more to do with their personality and temperament than it does with their intelligence or expertise (IMO).
It's about presenting dedication, not being correct.