Is it usual for graduate programs not to find suitable candidates even among a large pool of applicants?
I guess my question is: is it usual not to find any suitable candidates from such a large pool, or is the admissions panel just being too picky?


As somebody who recently did not hire a single candidate from a pool of about 100 applicants, I can say that it is indeed possible that they just did not find enough good people.

We were looking for a PhD student in computer science, with a focus on software and cloud engineering. We put out announcements to a few of the widely-distributed mailing lists in the field. Here's roughly what happened:


A few candidates had completely inappropriate backgrounds. E.g., one applicant had a master in biology.
About 30% to 40% of the applicants were computer scientists, but with a completely different specialisation in their undergrad and master. For instance, many students applied who used to work on theory, AI or Machine Learning. We are not interested in such backgrounds.
Easily more than 50% of the applicants, based on their application material,  did not have a sufficient command of the English language.
More than half of the applicants came from Asian universities where we did not know the university nor the professors writing the letters. All of them had reasonable grades and positive but very generic letters. Most had done internships at companies we have never heard of. As we had no way to distinguish the good from the bad students with those (to us) seemingly identical application materials, we deemed the risk too high.
About 25% of the applicants had, or pretended to have, multiple papers in predatory open access journals. The few times I actually looked up these papers, I was either unable to find them, or they were obviously of very low quality.
The vast majority of applications were supremely generic, and obviously sent in identical form to any PhD student posting in a Western university.


At the end of the day, we found 3 or 4 candidates that we were genuinely interested in, and after Skype interviews etc. it just did not work out with any of them.