While the index of coincidence for the D'Agapeyeff cipher is 1.812 when taken in pairs horizontally (e.g., '75' '62' '82'), the letter frequency distribution is too flat for a 196 character message written in English.
Each are approximately 100 characters in length and have an index of coincidence much higher than what is expected for English plaintext.
The structure of the D'Agapeyeff Cipher has similarities to the Polybius square, which the author used as examples in his book.
He explicitly solves an example of a Polybius square based cipher from a friend in his cryptanalysis section of the book.
When deciphered with a Polybius square, the plaintext of this exercise contains a mistake (based on mis-encoding "E" as "BE" rather than "CE"), but reads: