Since Prodduct Marketing is in charge of messaging (internal / and guidance for external) has a really good value with Product Management for translating the usability, functionality and benefits of any product. Product Manager should be more focus on release products, and Product Marketing focus on translate that products into the correct message (how it works? or how that product should be used?).
Btw Product Marketing should understand users/consumers needs for transmitting them to Product Managers and the products can be improved or develop new ones.