MMA is a grappling sport. Yoel wouldn't have been that good if he didn't have a life time of top shelf wrestling experience.
He would have been the average fighter who knows a little bit of everything, getting dominated by an experienced wrestler who started MMA late.
After watching Chris Weidman vs Mousasi and Maia vs Masvidal, I am even more convinced that MMA is essentially grappling with just enough striking to allow a fighter to grapple.
MMA does not require higher level striking, it is more important to have higher level grappling, because a grappler scores points with takedowns, positioning and attempted submissions. But a striker doesn't get points for good footwork or strikes that miss.
Conclusion, it is better to be a dominant grappler than a MMA fighter who knows a little bit of everything.