Can you clarify for me, a non-native speaker, what you mean with hustle here? Energetic activities or fraud? (I guess the first, but I also heard of a lot of academic frauds)

Connections and hustle are stuff you can learn. At least enough to become a professor. Most of my nerd friends who became professors learned these during their PhDs. I didn’t say they became famous professors just folks doing decent research in different corners of academia. I’ll still get my house in the subject GRE as the single most important metric if I were to choose a grad student. Not that I’m in that game anymore of course.