A question that always gets discussed is how much technical knowledge a project manager, my view apart from some extreme cases where you need a deep technical understanding such as engineering, the project manager to perform their role effectively needs next to little to deliver successful projects.
Working on the assumption that the PM is relatively intelligent (and to be qualified they would be) they would be able to quickly build a good general understanding of most industries and organisations.
The skills that the project manager brings in identifying and facilitating stakeholder discussion, formatting plans and then driving through delivery should outweigh the skills of a product expert.
So what are the dangers if you do have a project manager who is an expert in the area of delivery
OFFERS OPINION ON DELIVERY
Once a Project Manager offers an opinion on delivery, they start to come part of the solution, they should allow the sponsor and the key stakeholders to agree the project objectives and success criteria.
Getting to involved at the start threatens the PM's independence particularly when difficult decisions may be needed or when a full and frank review of what went wrong is required.
PICKS UP KEY DELIVERY TASKS
There will be always the temptation if dropping behind the plan for the PM to pick up tasks themselves to keep the project on track. This will inevitably lead to the core project tasks getting neglected and as with offering opinion on delivery there is a clear clouding of roles and responsibilities in the project delivery.
ASSUMPTION OF KNOWLEDGE
When you as individual know something there is always a tendency to assume that others have the same level of knowledge, and key needs such as communication and training can get overlooked. Having knowledge also loses the PM ability to ask stupid questions, which are always great to make sure everyone understands what the deep geeks are talking about.
PROJECT NEVER FINISHES
If the Project Manager is an employee rather than a contractor, the chances are that as an expert they will continue to work in the area, where the danger is that the project manager will continue to be involved in whatever has been delivered, and effectively causing the project to never finish!
