What have noticed from his style though is whenever he has the character in a side view, you don't really see the neck form the back of the character's skull (head). The neck just goes straight into the jawbone area. It makes the back of the head feel squished, at least to me. He did do draw the back of the head for Marten's girlfriend Dora, but for Marten it is not visible at all. Jeph has been doing this for a good while, and I thought it would be interesting to see what it's like with the neck line forming the back of the skull.
While attempting this exercise, I wanted to draw in Jeph's style, to hopefully make my observation more solid. For me it feels more fleshed out and full.
Now, I am not trying to bash Jeph's work, he does great stuff with Photoshop and his craftsmanship of characters. I felt that there could be something more added to his structure. It's a try for sure.
Hope you enjoy this exercise I did. :)