As a specialist in customer/market analysis and marketing I can say that I've never seen a marketing department that needed more than 15 persons to do what's really needed. I've seen marketing departments with hundreds of employees.
Please Google "Parkinson's law" to get to know why.
I remember reading a book called "Code Complete" years ago by a software expert from Microsoft. It's a decent software book, but the thing I remember most about it was the forward where he described Microsoft when it had about 100 employees. If I remember right he said about 10 of them were engineers and 70 were marketing!