No-one knows everything so the broader you investigate the better an answer you get.

What becomes problematic is when you get one person assigned to your team and they have either the wrong knowledge set or a contrary view on how things should be done to the project team. 

A classic example is the person who starts to defend the status quo in a department rather than assist in getting a clear view of how things happen. 

Another case is where people don't understand the context of what they are doing and so their focus is on local qualty loops and clientsatisfaction, and the balance against cost mnagement or strategy is lost.  Their explanations of what and how and why things are done can be plain wrong.

A third case is the person who is assigned but doesn't allcoate their time to you because they have prioritised other work.