I recently went through grad school applications and waded through dozens of sample essays and tips for writing a great “statement of purpose essay”.

Based on the admissions decisions the school made (as reported by Reddit) and the changes to content length made over the years, I suspect the school cares about precisely four things.

- Can your write a coherent essay?

- Can you clearly state what your qualifications to pursue the academic program are?

- Can you clearly articulate why you want to complete a 3 year program?

- If there is a problem in your background e.g. a low GPA, can you clearly state why you don’t think this will be a problem going forward?

I suspect everything else was entirely ignored.

Graduate admissions processes are very different from undergraduate admissions in exactly that way though. Undergraduate admissions are trying to select on a pretty wide definition of "successful", basically trying to find students likely to graduate then make the university look good. Graduate admissions care about one thing only: how good are you at generating published research in the department you're applying under. It's much more similar to a job application than an undergrad application.