For anyone still interested in this subject, I have just released a much better version of the Diary plugin, v3.5.0, that includes a much larger number of statistics. It can include capability for an autorating for one of the following: None, Characters, Words, Sentences, or Paragraphs.
Eventually, I hope to make it possible to select up to all four items for inclusion in the autorating results.
Eventually, I hope to make it possible to select up to all four items for inclusion in the autorating results.