That doesn't seem too bad. I generally think that ten people is about the upper-limit of one's ability to effective directly manage a group, so to that end having one person serve as the "art director" and primarily oversee and coordinate the artists in various ways seems reasonable. Having one person focused on business and legal issues is also not entirely uncommon.
I would expect at least one more producer/management role to both interface with the art manager and to manage the "other" development roles remaining (programmers, etc). So three management positions seems totally fine. Four, where the extra is another production role, seems like it might create a bit of overlap but it isn't egregious. Especially if these production roles are also contributing in other ways.