ERP Projects
These projects are important and expensive. Maybe, you do not have a lot of experience with such projects and you do not want to depend completely on IT specialists or external consultants, because both are part of the project. That is why you want to reduce the project risk by engaging with an independent ERP expert.
Complexity Management
ERP systems are the logbook of your organizations and therefore show the complexity (or complicatedness) of your real operations. You want to use this knowledge to reduce the complicatedness in your company.
Project Manager
You coose your project manager because he has good qualifications and knows your company very well. Well done! This is a much better choice than to use an external ERP specialist as a project manager.
But this PM has limited experience in ERP projects and you want to support the project with an ERP expert coaching your assigned PM.