Social media marketing manager: a trained professional or an expert of information technology?

Perhaps top social media marketing manager should possess both characteristics: be a marketing and communication professional, preferably with a degree, and have good skills and knowledge of web tools and informatics.

Needs to break down the role in two forms:
1) social media: knowledge of social networks and their tools to comunicate;
2) marketing: skills in market and customers target analysis.

A top social media marketing manager should also possess good knowledge of blogging, videomaking, website development.

What skills should a social media marketing manager have?