There's a lot of talk in the Scrum world about metrics. What's the velocity? How big is a story point? How many story points is that team producing per man hour?
People are sadly missing the whole point. Take your measurements up a level or two. When you get down to it, the only metric that makes any difference, is ROI.
The problem is that often times, the developers work in a dark hole, far removed from the realities of how exactly they get paid. A bigger problem is that mid-level managers tend to be further removed from the realities of ROI. A lot of times mid-level managers get tasked with tracking their teams "productivity" using things like, "lines of code", or "completeness of the productivity reports."
Monetize your projects and then track your velocity against business value (real dollars).
When your development teams can say, "Last year, our team cost the business 2 million dollars and we know that because of our efforts, the company saved 2 million dollars in waste and increased revenues by another 4 million dollars."
At that point you have just moved your development team from a cost center, to a profit center. You might have to give them a raise, but they have demonstrated that they have earned it.