I agree that the Dalai Lama should not have gotten involved in recognising the 17th Karmapa. Well, instead of gaining more "control" over the Karma Kagyus, they have created more schism, and more disunity and another a group of people who dislike the Tibetan leadership. Not a smart move at all.
I don't think they have failed in maintaining unity, because I don't think that is something they wanted. If we look at CTA's track record, they clearly show us that unity is one thing they do not know how to or want to cultivate/encourage in their society, which is sad coming from a so-called Buddhist community with a spiritual leader that the world sees as compassionate. Totally an illusion, total opposite of what they claim. More and more ugly truths are going to be exposed. This is karma returning to them in full circle for the injustice persecution