Chelsea did do reasonable well in the shirt sales in 2012-2013. Their influence in it was decent, but not up to the standards set by teams like Manchester United. Only having 2 players in the top 10 sellers, Chelsea could not have generated enough income from this branch. Also, despite Eden Hazard being a fantastic player, it was his first season. His shirt sales are likely to decrease as time goes on.
In the 2012-2013 season, high bets was placed on who would be the better buy, Shinji Kagawa or Eden Hazard. Whilst I feel that Eden Hazard excels in the attribute of skills on the pitch, its Kagawa's international status that makes him the better buy. Selling more shirts than Hazard, Kawaga will be more likely to make back the money spent on him. Eden Hazard is less likely, unless Chelsea step up their game for the trophies.