I'm sure Mrs. Coble had a lot to do with this
Most interesting thing about the article:
"He seemed on pace to return in the fall. But his rehabilitation caused an apparent conflict that led to multiple meetings among Carmody, Coble and Coble's mother, Carlys."
Coble's mom is an attention hound the likes of Mateen Cleaves' (late) mother from the late 90s. Well before her cancer diagnosis, Mrs. Coble loved the cameras, to the point of nausea. Nothing changed after the cancer diagnosis. I get the feeling she's one of those parents who thinks she has all the answers (see Humphries, William: Minnesota), and let Carmody know so. I'm guessing Carmody -- to his credit -- didn't cow-tow to Mrs. Coble. Can't be sure of the reasoning behind the decision, but Coble's quitting has a definite stench to it.
Bottom line, no matter how you slice it, this is a huge loss for Northwestern. Coble is a unique player and he will be missed. His mom mugging for the cameras? I'm glad we've seen the last of that.