The teams should be lined up so that the incentives for your vendors should also be lined up with the incentives for your internal team. You're right that the sourcing piece is important. However, the stewardship after the deal is signed is where your value is either going to be created or lost. It's probably 40:60 or 20:80 in terms of effort, but very little effort goes into the stewardship of the relationship and the management of it.
On February 13th, 2018. See this statement in context.