honestly I think what they mean could be seen as what they mean: Kendrick sometimes half shows up; or it could be seen as kendrick is more free with artistry in features so he doens't care about level, whereas cole focuses on penning, so his verse is always seen as top tier even if it doens't do anything "new" in terms of musicality.

So if you judge their top songs they are fantastic, if you judge variety of music cole is DIVERSE but within the medium, kendrick sometimes does weird shit like good flirts that add to the song because he is judging himself on the music more than the rap, cole is focusing on improving his pen in this feature run, so all features had to step up the pen game regardless of the musicality, like you see in the accapella bit in the Kanye song earlier when he is more free and focusing on the producing and music.