Why chart the emotions of the protagonist to evaluate the story? The value of a story is not in how happy or sad the protagonist was - but how it makes you feel.
It's a rather good starting point for analyzing stories. Most of the stories he mentioned (with Kafka being a notable exception) aimed to make the reader identify with the protagonist. Therefore, it's the protagonist's situation that matters the most. Also, bear in mind that he wasn't charting the emotions of the protagonist, but the protagonist's fortune.