I had Cousins as my number 1 on top 10 centers under 25 last year but I've soured on his game, ridiculously high usage rate, wasted possessions and he shoots like shyt from the field. He's so turnover prone ontop of not being a great defender, and while Drummond isn't elite on the interior he is better than Cousins defensively and the Pistons are a top 5 defensive team right now, while Cousins has never been apart of even a decent defensive team.
He's starting to trend more towards being a stretch PF than a center, 34% of his shots are now coming from 16 feet to beyond the three point line. At this point I'd rather have Drummond, his highs arent as high as Cousins but I know he's not going to turn the ball over 10 times in addition to taking 31 shots, Drummond is just more stable. Cousins is just as likely to turn the ball over or shoot you out of a game as he is to win one for you.