The article below does a great job of discussing some of the challenges middle managers and resource managers face in Agile organizations. The increased matrix structure and the fact that resource managers have less day to day interaction with their direct reports (because they are distributed across multiple agile teams) can lend a surreal quality to the role! “What am I supposed to be doing?”
Aside from a strong emphasis on servant leadership for all managers thoughout an organization, I’d also humbly suggest that resource managers and scrum masters / agile coaches partner around team member objectives and progress toward them. It is not always easy for managers when doing OODA to directly see how their people are performing in their teams (especially as the members of a team may each report to different managers).
Scrum masters, though, do directly and actively observe team members every day and so having a common understanding can help insure appropriate mentoring (and tools,training, etc) are provided between scrum masters and managers.
The mission of middle managers might be phrased as enabling people to flourish so that their teams will also.