I ran a webinar yesterday for a potential customer and one of the questions was: Is there a service manager role in YaSM?
We do not use the term "service manager" in YaSM, but some organizations may decide to introduce this role if there is a need. The point is that "service manager" is not a well-defined term and it can mean different things to different people, so if you introduce this role you have to properly define its responsibilities.
In YaSM we refer to service owners. This is a key role in the YaSM framework, because service owners are responsible for delivering the services according to expectations. So we could argue that the service owner is a kind of "service manager".
But I have seen organizations that have both service owners and service managers. In these organizations, the service owner usually has overall responsibility for a service, while the service managers are responsible for managing certain aspects of the service. An example would be a service manager taking care of shift planning and staff scheduling.
So, while we would strongly advise not to introduce as many roles as possible, there can be a case for a service manager role; it will all depend on your specific situation and the kind of services you offer.
Stefan (YaSM community moderator)