Rewatch the RDA fight, the fight was fairly uneventful before Eddie landed that hook. It was a bit back and forth, with nothing significant landing for RDA. Eddie caught him with a hook because RDA was pressuring Eddie and Eddie has great footwork and set up the shot, ya know, like a professional fighter with a lot of knockouts under his belt. Nothing lucky about it, RDA got caught, it happens, if they fought again it might happen again. Hes got some of the best boxing in the division and is damn tough to take down or knock out, there is nothing easy about fighting that man. He gets beat by good boxers who have range on him given his short reach, and he did exactly what he needed to do in the fights with Melendez and Pettis.
Jon Jones gets called the GOAT, but some of his fights like the one against OSP were pretty lackluster too. At the top there's such a small margin for error, not every fight is going to be a fight like he had against Gaithje or his fights against Chandler, but to say anyone other than Conor should have an easy time with him is just fucking stupid.