Well I have worked in companies making physical goods (shipping millions every year), and you just don't buy a team from one day to another. It's not just about production, it's about supply chain, it's about quality management and quality assurance, regulations for sale in different countries/states, market research, product qualification to improve the design, actual customer support, vendors, distribution, etc...
It's a whole new area of skills/functions you don't have, and that does not mix very well with a software-only company mentality. I think it's going to be very tough for them to make something solid with Facebook.
EDIT: They would have been better prepared for scaling with a company like Apple (whose main business is already making hardware), Microsoft or Google for that matter. Many people say Valve could have been a good choice, but Valve has said several times they don't want to go into the hardware business (and won't make Steam boxes themselves).