It is a good measure of
productivity as long as StoryPoints are about size of the
product. A good size metric is functional tests passed, or
scenarios releases, or even use cases releases. It is
interesting to think about how to measure the size of the
delta between product increments. But, since we know we
are incrementing the product, there should be some way to
measure it, right? That is productivity... how big is the
increment delivered each sprint? If you can put numbers on
it, this is velocity.
Yes, that is velocity. And it is wrong. It's wrong because:
It can be misused, and usually is;
It can be gamed, and usually is;
And most of all, because it is working on the short end of
the lever. What's important in Agile is steering the project
by selecting things to do and things to defer, not working the
cost side of the equation and trying to improve it.
A team that is focusing on velocity is not focusing on
value. I wish I had never invented velocity, if in fact I did.