I have seen a lot of times in my career and have also learned from the experiences shared by others that a Senior member of the team who is Technically very sound is being made the project Manager for an up coming project . Reasons given mostly are :
1. The person has fdeep knowledge of the project
2. The person is very good technically.
3. The person is working in the same time for a long period now and needs to be elevated .
4. The client is very happy with his work .
This is the biggest mistakes Organizations make . Rather than judging the project managemen capabilities of the person XYZ , they elevate a person to a Project Manager basis other factors which leads to a FAILURE .
This is called as HALO EFFECT .
Hope next time you need to take such decision you will remember me and the HALO effect