I think this number should be left alone for a while. It's endured world of abuse these past years (Kezman, Crespo, Boulahrouz, Sidwell, Di Santo, Torres). http://www.thefootballsupernova.com/2012/01/curse-of-chelseas-number-9.html I think let's leave it alone, let it rest from all the shame, and revisit that number when the time is right. 19 suits Costa very well imo, he could make it his own.