His fight against Gus is the supporting evidence for DC's cardio here
After being KO'd literally, he won the fight on everyone's score card except one judge and one media member (the majority of fans and media thought he 49-46 or 48-47d him, so the same margin that Jones beat him).
This is the same Gus that took Jones 25 and many people thought he won, and Cormier actually ramped up offensive output and broke Gus down the stretch. He was certainly tired, but that was arguably just as high pace of a fight as the Jones match and Cormier did look improved and won down the stretch with pressure. Plus getting rocked is probably one of the worst things that can happen to your cardio.
Factors again, Jones gassed DC more actively than anyone else can do in that division through active clinch work and body kicks which no one else but Jones in a rematch could replicate - so that's to consider as well.