His age limits the value of any "prove it" deal and reduces the likelihood he's going to truly prove it to the point where he's able to cash in big on it. Meanwhile, he's inexpensive enough now that the Rams would likely get decent value out of him for a couple or few years even at a little more AAV than the one year deal gives him.

Seems to me the right deal for both side would have been a modest 3 year deal that gives Barwin some post 30's security and the Rams some cost certainty for the near future at the position.