If you think about it carefully, you just made an argument for, and against Cousins at the same time. One could say, that if he's so great, why hasn't he made a bigger difference. I'm not saying that, just playing devils advocate.
The Kings were a terrible team before Cousins arrived.
Cousins has become a top 10 or maybe top 5 player in the NBA
The Kings are still a terrible team.
The obvious conclusion to be made there is that Cousins doesn't negatively impact the team but also doesn't uplift them in any way either, something we'd expect from one of the best players in the NBA.
But there are zero players still on the team from before Cousins entered the NBA.
Unless we count a half season of Casspi, Cousins is the ONLY player left from the Kings team his rookie year (2010-2011)
He's the only player left from the 2011-2012 Kings team
He's the only player left from the 2012-2013 Kings team
He, Ben McLemore, Rudy Gay and Quincy Acy are the only players left from the 2013-2014 team and Acy left after that season
We can look and say that the Kings have been terrible for all of Cousins' six seasons in the league and that he's been the only constant. And while that's true, it's an incredibly lazy argument.
Probably the best measure of how much of a difference Cousins makes is how the team plays without him. And there we see another pattern. If I have to I can look up the exact stats but for years the Kings have been far, far worse with Cousins out of the lineup than they have been with him on the floor. Our previous GM flat out said the team was "Philadelphia bad" without Cousins. In his mind that was an indictment of Mike Malone's coaching but to me that's an indictment of the rosters that have been assembled over the last six years.
When the roster gets turned over at the rate it has, draft picks are busts over and over, free agency doesn't bring help, the few quality players allowed to leave for nothing and year after year the record is so terrible without DeMarcus then maybe it's not DeMarcus that's failing to make this team better.