We have a really good assertive Scrum coach on site. The impact can be felt almost immediately. We had a PM who was learning how to be a ScrumMaster, but she really wasn’t getting any serious feedback on how to handle the nuances of Scrum. One day after our Scrum coach started working with her I got a phone call about 9am.
She wanted to know if we could get some help deploying to our Websphere QA server and who she needed to follow up with. I pointed her in the direction of one our sysadmins. The phone call was no big deal really, but it was the first time for the whole Sprint the ScrumMaster had taken on the responsibility for removing an impediment. Since our PMs are by default put in more of a project admin role, switching to the team protector as ScrumMaster is very different.
The nice thing is with just some feedback from our Scrum coach, this PM instantly became a lot more effective.