Yale professors' ideas of being knowledgeable in a subject come from their experience lecturing students.
I've been getting paid to do programming for almost 30 years. Google has changed programming such that you no longer have to memorize the useless trivia that college professors lecture about.
As a result I can focus on improving my ability to program as a generalist, and I'm very good at what I do. If you asked me to write a bit of non-trivial code in anything but pseudo-code, I would very likely not get the syntax exactly right (unless you asked me to write it in C, which I learned before the days of Google).
Google allows us to not be smart at things that are a waste of our time to learn in the first place. We can have a much more broad knowledge of many subjects and use Google to drill down on specifics, rather than having the type of knowledge that professors crave, being completely pigeon-holed into one speciality where you have all of the trivial detail memorized.
Can I rattle off every type of tree structure, and tell you what tree is good for what problem? No. In the days of Google, that type of knowledge is useless. You ought to know when you need to use a tree structure of some sort and you can spend an hour or two making that determination, or if the decision is critical you can spend a day on it. Effectively, those weeks or months we spent in computer science/computer engineering classes learning all of these very specific attributes of data structures were a waste.
To generalize, consider everything you can easily find with Google to be part of your knowledge. Memorizing it would be a complete waste of time. But that very waste of time seems to be what these professors were measuring (and valuing!)