Strategy occurs across three different levels in the organization: at the top, where it is created; at the bottom, where it is executed; and in the middle, where strategy from the top is translated into activities achievable by the bottom. The PMO and portfolio management exist in that middle space. Lindsay Scott discusses this in a post at Strategy Execution, where she refers to the PMO and portfolio managers as the “center leader.”
The center leader does not just direct executive edicts at teams though. It also reports program and/or project progress in a contextual way, to assist business leadership in deciding when adjustments must be made to strategy or its execution. Discussing the PMO in this manner should make it easier for people in the organization to understand the crucial role it plays.
For further implications of this manner of thinking, you can view the full post here: http://www.esi-intl.co.uk/blogs/pmoperspectives/index.php/the-pmo-as-the-centre-leader/