Vendor management is the pro-active collaboration with your product and raw material supply base. Successful collaboration allows constructive joint problem-solving and avoids many of the ills associated with vendors being left to manage themselves.
But whether you are engaged in activities such as developing and controlling cycle times, controlling allocation plans for multiple vendors, studying and discovering economies of scale the real question is can you really ever afford not to be fully aware of all aspects of your production supply chain.
The overall strategy is to have clear accountability through information sharing.