And yet, there will also be false positives.
I did poorly on one test. Noticing this, I studied hard and greatly improved my grade in the next test. Would this flag up a warning that I'm a cheater?
Or for that matter, doing better on the 'harder' questions. Perhaps I decided to concentrate on doing those questions because they offered higher marks than the easier questions, or because I had a natural aptitude for some elements. I may have elected to study those materials harder.
Professors can't rely solely on 'statistical anomalies'. Illogical patterns may well have an explanation that has nothing at all to do with cheating or advanced knowledge of the test. Of course, we all know just how lazy a minority of our lecturers are.... and how likely they'd be to take the word of this agency as gospel.