I'm not sure your average English word has as much as five characters on average. Okay, let's count this paragraph. 91 characters, in 21 words. 4.3 character

I'm not sure your average English word has as much as five characters on average. Okay, let's count this paragraph. 91 characters, in 21 words. 4.3 characters on average, which would mean 13 bits of entropy. I don't believe it. It sounds like your source didn't account for word frequencies in real sentences, let alone grammatical constraints.