I'm enjoying this discussion despite our slight differences, by the way and I acknowledged your Johnson point as I was drawing it as reference.
Now...
Would you not be worried if Iaquinta came in on one day's notice, stopped takedowns AND lasted 5 rounds?? I think I would be.
Johnson, as far as I know isn't a wrestler, which is why he likes to keep it standing. So, for me, to 'trade' with a piston punching target finder in Gaethje would be an absolute mistake even for a few minutes.
Gaethje sprawling would take less energy than the effort to takedown. I've seen it so many times how the 'gas tank' depletes with unsuccessful attempts.
And, yes, I agree that Gaethje got outwrestled by Poirier and Alvarez, but he wasn't focused in that period. He was there for the fun fight. As the Ferguson fight showed, he's changed.