A&R stands for Artists and Repertoire. The is the division of a record label that is responsible for talent scouting and the artistic and commercial development of the recording artist. It also acts as a liaison between the artist and the record label.
www.musiccareers.net
Mostly they are the team that picks and grooms songs at a place like SM since they do not really recruit existing artists.
money quote
A & R can sign new or established talent to the company’s roster. They then continue to work closely with the artist, acting as their liaison to the label’s
business affairs department and as an advisor who will help nurture a certain sound and image Their duties include listening to demos, aligning artists with the right producer, and offering creative input.
For the unsigned musician, A&R can be the gatekeepers of the industry. It is not their job to keep you out, so much as it is to find marketable music for their company. A&R reps are the musicians’ point of contact at the label during contract negotiations. They also play an important role in development of the artist – how the band will be marketing, sometimes choosing songs for the musicians to record if they don’t write their own material and building a basic promotional foundation for the album and the band.
The problem i have is any one would have known that that song was not going to fly with the general public. PU was successful but nowhere near any of the previous 'red' songs. They needed to come with a money song and they blew it. Badly. Really really badly.