Yes I think we are on the same page.I get what you're saying, and I think we're pretty much on the same page.
First, every person who steps into a UFC Octagon is skilled, even on the undercard. Which dovetails nicely into what I was trying to say. Now, to be clear, I can only really speak to grappling, as that's what I know.
Skill beats size, strength or raw athleticism in almost every single case. I've seen this proven over and over and over again.
Physical gifts plus some skill, however, can overtake skill by itself very quickly. So, a moderately skilled guy who is bigger, stronger, more aggressive or whatever can overwhelm a highly skilled guy who is smaller, weaker or whatever. But where it's strictly skilled vs unskilled, skilled wins almost every time.