Intuitively sure, but would be nice to have some data to back it up; my intuition could say otherwise. Also, even if they're different how do we know how the correlation works? The article claims there is either no correlation or negative correlation. How do we know that?
Poorly defined problems often come down to things like creativity and your ability to handle emotions. Sometimes you have to follow a seemingly senseless curiosity to find the right path forward. Sometimes it is about finding beauty where it isn't expected. Also these problems have multiple valid and fundamentally different solutions and can be highly subjective. Think art.
Well defined problems are about juggling multiple things in your head, high concentration, relying on fundamental knowledge, heuristics etc. All of that possibly under pressure. There might be multiple solutions but they are typically on a scale (good enough vs perfect etc.) or are choices between measurable tradeoffs. Think engineering.