Kanye has been pretty honest about his abilities as a producer. He was always a chopped-up samples producer and started bringing in musicians and other producers to layer original instrumentation over his samples on his first album. That style evolved with each subsequent album, with his albums prior to Yeezus being extremely orchestrated and huge.

There is absolutely no-doubt that Kanye is the ringleader in this. He puts a bunch of people in a room, and while he may not be the person pounding the keys, but he's putting it all together and making it cohesive.

I can listen to the Hudson Mohawke / TNGHT song that Kanye used in "Blood on the Leaves" and think it's an okay song. But the way it comes in on Blood on the Leaves with Kanye's rapping and the "Strange Fruit" sample left me floored the first few times I heard it. He made those TNGHT so much more powerful.

Kanye's influence over rap is enormous (the singing rap thing that Drake and others are using really didn't gain mainstream attention until 808's) and he's extremely successful commercially. It's not accident, nor is it the simple result of others' work. It's the work of someone who is meticulous in his craft, knows his limitations, and respects the work of others while pointing them in the direction he wants to move.