Jon Conner shouldn't have signed to Aftermath, that's the biggest problem. He can't release anything without a greenlight from the label, and has probably recorded hundreds of songs that will never be released. It's not an issue of being lazy, he doesn't control what comes out or when. IIRC he has released two mixtapes since signing to Aftermath, both of which aren't noteworthy (they continue his "rap over other people's beats exclusively" gimmick).
He released a lot of mixtapes sure, and they didn't garner much attention. However he never really did a project that demanded attention from rap fans. His album has some noteworthy features (Gibbs, Royce) but the production is forgettable. Doing a project with Black Milk would have made perfect sense but nope.
Same shit with Elzhi, man. You can't win while being from Detroit and not working with anyone.