Yeah, it's Niang. Nothing to do with 2 Nba starters sharing the floor with bench unit.
Dude Niang was a huge freaking problem for us. I don't know how anyone can be blind to it. He didn't rebound, couldn't defend, created zero in the way of hustle stats (offensive rebounds, steals, blocks), couldn't pass, couldn't drive/draw fouls/post/do anything offensively within the arc, he committed boneheaded fouls and gave up and 1's.
Go back and watch Royce Oneale in that first half again. He literally did all of the things Niang can't.
Sure rotations matter. And sure having two starters in the game helps. But basketball is a simple game. It's all about your 5 outperforming the opposing 5. And to do that you need players who provide a variety of positive attributes. When you have a guy like Niang who ONLY provides 3 point shooting you are basically asking the other 4 guys on your team to beat the opposing 5 in every other category.