> This is a quantified reduction in ability

How effectively is it controlling for factors?

> A lot of programs are admitting under prepared students.

Sure. But there remains the question of _what_ should the students be prepared for, and are educational institutions providing that substance? Meaning, are students under prepared because they don't know how to succeed in a college environment, or are students under prepared because colleges don't know how to teach in a modern environment?

They’re underprepared because they weren’t adequately prepared beforehand.

The only thing I noticed quantified in this paper was the number of students failing. Could just as easily be explained by a decline on the teacher's end.

Considering that the same system is producing both students and teachers it seems very likely that the quality of both could be declining in a feedback loop. Less prepared instructors produce lower quality students who are themselves poor instructors.