This would probably be a good Facebook quiz, along the lines of "Which Big Bang Theory character are you?", but I'll focus on the types and not actual people. And for the exercise, I'll borrow two characters from the popular show, the Big Bang Theory.

In the show, Sheldon Cooper is a theoretical physicist, who focuses more on overarching theoretical ideas in Physics like String theory. And Leonard Hofstadter is an experimental physicist, who focuses more on designing experiments to validate hypotheses and theories (where the hypotheses and theories are usually proposed by theoretical physicists).

In Product Management, these are two extremes. One is a product manager who specializes only in spotting macro trends and making higher order strategic decisions on where the product should go and who it should serve. The other kind specializes only in iterative experimentation for short-term exploitation and optimization of metrics (usually conversion).

A good product manager lies anywhere on that spectrum and can usually do one of those things very well and the other well enough to not need outside help. If the product they work on doesn't match up to their area of expertise, then that product has a very poor chance of succeeding.

If you work in product management, you need to ensure you are working on a product that relies on your area of expertise to succeed.