RDR might surprise us. I'm not saying you can't be right but recency bias is very real. No one exactly thought Khamzat would show up with the gas tank he did with DDP when Khamzat had been shown to have suspect cardio in all his other fights too. Before the DDP fight with Khamzat and before the Rob fight with RDR, I don't think anyone would make the argument that RDR or Khamzats cardio would be an issue for either if they were to fight.
Why not? RDR has BJJ at a level comparable to Burns and Fluffy's is one of the best wrestlers in the division.