they were a much bigger mess with Cousins at 4.
and don't judge solely on that. he's very agile for a 5. at 4, he's slow.
when he's not too lazy, he can play awesome post defense. he can't defend most 4s.
he has great post game (reminds me of Sabonis tbh). he's extremely inefficient in the high post.
he's as strong as any center and embraces contact.
why would you put him at 4? the only reason is if you have another great 5 and no decent 4 whatsoever.