Key things to look out for when recruiting for a Project or Change Manager is someone who has good knowledge and understanding of project and programme management methodologies, project control tools and techniques, and their practical applications.
Professional qualifications in project management, such as PRINCE2 or PMP are useful. So too, is a demonstrable awareness of change management techniques. You want to hire someone who has provable experience delivering a complex or multifaceted project with Agile methodologies, who can therefore react flexibly to constantly moving parts of project delivery.
Of course, deep technical understanding of the technology they will be delivering, or optimising is a must have. Soft skills are also important, especially communication, senior stakeholder management, negotiation and influencing skills.