It would be a blessing if dude was at least mediocre. But he's so goofy bad, that he ruins damn near any song that he appears on.
He has no sense or feel for music or the tone of a song. He just tries to spaz out with the goofiest bars & voice known to man.
Somebody mentioned that he almost died and had to learn to rap again. Is that a real thing? At least that would be a good explanation of what happened to dude.
I always thought Eminem was full of shyt whenever he said that. I mean, he was two hours away from dying (after the overdose) but he always said that when he was doing Relapse, he was teaching himself how to rap again. That album doesn't sound like he's feeling himself out. The serial killer concept, bending words to make them rhyme, the different flows he used. If that's him teaching himself how to rap again, then he's way too hard on himself.
I don't think it's a coincidence that he dislikes that album so much, or has mixed feelings about it. Since then, he hasn't made anything that sounds like it. I get him avoiding the accents, but everything else he did on that album, he could have easily done on Recovery or MMLP 2. I don't know why he thought screaming, punchlines, and chopping up his flow was what he needed, but I seriously don’t know if he can help it. He might actually be incapable of doing anything besides what he does now.
He probably listens to his older albums like

because he didn't stretch out the rhyme schemes enough or speed up his flow so he could cram some more bars in there.