[nradov]

Where are the customer circles in that diagram? Product managers have to get out of the office (maybe virtually) and talk directly to real customers and qualified sales prospects.

[crazygringo]

A full diagram has a circle at the bottom for customers and a circle at the top for management.

The PM is the hub of communication between all 4.

Although on a day-to-day basis, it's the dev team and business/sales that make up the large majority of interaction.

Check-ins with management are occasional, and conversations with customers are just kind of an ongoing informative thing.