Probably dropped him because he wasn't doing a good job in negotiating.
Also Arturo Canales, brings so much more to the table. from what MD say he knows quite a bit of the wage structure and his experience in handling both Pique and Rakitic will certainly help out Umtiti.
Today I read somewhere, that he said something like if it were for him, he would definitely renew and that he lowered his demands. (i don't know the source anymore)
Better just wait and see what happens.