Print brokers and managers have been around for a while. In fact, some of the most successful companies in the industry don't have any presses of their own.
They scour the market for their customers to get the best deal. They make sure that each project is produced on the most appropriate equipment and because they have a wide ranging supplier base, they have access to just about any printing press you'd care to think of. No individual printing company would be able to address every printing need but brokers can, through their diverse supply chain. They keep prices down by using trade-only suppliers and maintaining low overheads of their own. Their extensive supply base means that they can always find the right supplier for the job: this benefits their suppliers by making a contribution to their overhead and it benefits their customers because of the reduced rates which they are able to acquire printing for.
Often though, a customer requirement will be very specialised or time-sensitive. In these instances, price is not necessarily the primary concern. In these instances, a print broker's customers will approach them because they don't know where else to go. They could undertake a lengthy search for the most appropriate suppliers but to free up their resources, they employ a management firm. As well as a general print management service, these companies are able to offer a service wherein their supply base allows them to provide pretty much anything, any time. They're print managers and exist as an out-sourced procurement service to their customers.