I've seen people who were better at written communication in English than verbal communication. It was easier to both understand them and have them understand me.
I think everyone would be at the same disadvantage, regardless of English competency, when it comes to 19th century English poetry. ;-)
As a self-taught English reader (recently listener and rarely speaker) I should note that understanding sound and rhythm of English poetry taught me so much.
I was able to semi-decently communicate technical things before I come to Shakespeare's "To be or not to be". It completely changed my view on English language. Before that I was reading English prose as a deformed version of Deutsch (language I learned at school). What worked for technical prose stopped working for verses. I had to dig deeper.
From my experience I think that someone who barely speaks foreign language cannot have an adequate opinion on that language verses.
And I think that GP is right about cheating.
The testing would have caught anyone who didn't know the material. Yes, they learned as a group and corrected each others homework, but they also put in lots of individual hours.
I went to a mid-tier public college. Certain cliques of asian students with no ability to communicate verbally in English were somehow able to produce amazing criticisms of 19th century english poetry.
It's difficult not to draw a parallel between people like that and the fraternity people (who were incapable of communicating in English for other reasons) who achieved similar feats.