Pretty much.
Look at it from an employers perspective.
You might win a ton of bids as an estimator but if they lose money with you as a PM ( because you tanked the bid or never PMed it correctly.) you are one giant liability to the company.
So yes, there is a value no matter what as being a good estimator and using the labor rates and margins that the company tells you to use.
Beyond that !?
It would take me a week to write the variables on what can happen on a job as a PM. Most of it is pre-damage control and anticipating all that can and will go wrong.