Where can PM provide the most lift in the enterprise sales motion?

Tactically, product managers can set the patterns that define successful customer accounts (e.g., via beta testing, early wins, clearly described use cases, &c.), engage with key customers to form lasting business relationships, and amplify the key customer problems.

This is why customers love to speak with PMs. What's best for the customer is what's best for the product, so PMs are seen as sources of truth. The PM will listen for problems, won't egregiously oversell the product, and speak to roadmap direction with authority.

Organizationally, product managers help Sales the most with honesty, empathy, and frequent engagement.

In my mind, we are always selling to a customer.  It starts with the initial sale, when we move an organization from a prospect to a customer.  Once they become a customer, our goal is to ensure they continue to renew their contract with us.  And not only do we want them to renew, but we also want to upsell them to additional products and services. 

Throughout the various stages, PMs should be there to support account teams as needed, especially around handling customer objections.  It’s very beneficial to establish strong relationships with the sales team and strategize with them on how your skills and expertise can be leveraged to move a deal/customer relationship forward.  Setting up prep calls with account teams ahead of customer calls is always invaluable to this effect as well.  Here are some more ways PMs can support the sales team on deals:

• Evangelizing the product - PMs serve as the source of truth for the product.  PMs can speak to the vision and roadmap, be the domain and product expert, engage in customer feedback sessions, and really help customers understand how this product can benefit their organization and use cases.
• Feature requests - Customers will also have new feature requests, some of which are nice to haves and some of which are considered blockers.  PMs will be engaged to discuss these, and may be more heavily involved when blocking features are identified that customers want commitments on before moving forward on a deal.  PMs are also the ones that should hold the line when feature requests don’t align with the product strategy.
• Customer escalations - Escalations can include gap features that are needed to close a deal, product features that don’t work as expected, or a heinous bug that greatly impacts users.  Whatever the reason, how a PM handles these tough situations and manages the relationship with the customer can make a big impact on the customer relationship and their satisfaction with the product and your company overall.

Being able to support 'repeat sales' is one of the hallmarks of a scalable sales setup. As such championing the product USPs with powerful demos that bring out the best of the use cases is a task only PMs are uniquely positioned to enable, sometimes even before the feature is fully built. 

Producing a small library of such impactful demos and talk tracks in collaboration with product marketing and presales has the effect of greatly amplifying the impact our product can deliver.

Product managers can be particularly useful thought leaders when impacting deals. Most importantly, in strategic deals it helps to have someone advocating and explaining the product that is not a sales person - because the customer or prospect feels they can trust the expert and not feel like they are being sold to. In this situation, you can represent a vision and product depth while also doing early selling.