@harvardandberkeley it might not be fair but it shows something. if the professor has switched universities then this says something about the ability of their current university to attract top talent. If a professor decides to leave Harvard and go to Stanford then that says something. Also Harvard is notorious for inviting nobel winners who have not done any of their research at Harvard, to be Harvard fellows in order to establish affiliation.
The alumni metric per se also doesn’t really matter that much. it matters more where they did their research and even more so which university they decided to stay at eventually. Point is, it is not clear cut.
Regardless of that though, Harvard is very much threatened by Stanford at this point. It definitely still has the most prestigious and recognizable name out of all higher ed institutions but it has some catching up to do to ensure it will be viewed as the indisputable top school in the future as well.