John Mansour puts his finger on an issue facing successful product managers: product knowledge is a double-edged sword.

Okay product managers, what has all your down-in-the-weeds detailed product knowledge done for you and your company lately?  Entitled you to more phone calls and emails?  Turned you into first line customer support?  Allowed you to write endless pages of detailed specifications that are more painful than a root canal minus the Novocain?  It doesn’t sound like product management.

Mansour argues that, for many core aspects of product management, product knowledge can be a liability for the product manager. Here’s an example:

3.  Defining Business/Market Requirements & Business Cases – It’s all about defining problems first, and product knowledge is not required to define a business problem.  Your target customers have the same problems today they had 100 years ago.  They just have them for different reasons.  Product knowledge is only required to suggest the most appropriate features for creating the solution. Detailed product knowledge = liability because it forces you more into "how" features should work instead of  "what’s needed and why" from a business perspective.

There’s one small problem here: your credibility as a product manager depends on your product knowledge. Developers and engineers can smell when someone doesn’t know how the current product works, or what is technically feasible. Before you can convince them to take on work, or make mid-course adjustments to what they’re building, you have to appear that you know what you’re talking about.

Once you’ve established your cred, the company is happy for the PM to talk about features and functions, instead of the business perspective, for reasons far too lengthy to discuss here. Suffice it to say, your product knowledge is always going to be useful for sales, support, training, and other important activities. Getting strategic, when your daily schedule is filled with tactical responsibilities, is pretty tough.

Short of finding something in your high school biology notes that could tell you how to pith yourself,  PMs have only a limited ability to say no. You can’t keep refusing to help with big sales opportunities and keynote demos.

Unfortunately, I don’t know what the alternative could be. I’ve had my moments when my willingness to be an uncompensated sales engineer or documentation writer snapped. Until management understands the price everyone pays for this misuse of product management, it’s a situation that’s likely to continue.

Here’s another reason why I wanted to study product management: no one doing product management can accurately depict these sorts of problems, across the industry, and calculate the costs to the company, not just the PMs. Companies have to reach the realization that misusing product management is like strapping a Saturn rocket to your minivan: Sure, it’ll get you where you want to go, but there are far better ways to use these resources.