Lesnar was fast tracked the title because of his pro wrestling fame. It had nothing to do with his wrestling pedigree. And it's not like his MMA grappling was anything to write home about either. Brock was getting controlled by a fossil who was 50+ pounds lighter, and wasn't even competitive against Cain outside his one meaningless take down.
That sort of proves part of my point for me, you see, you mentioned how Brock was getting controlled by a "fossil who was 50 pounds lighter". That says nothing about Lesnar's MMA grappling relative to Ronda's. That proves just how much less legit WMMA is than its male counterpart - Lesnar was a more powerful grappler in MMA than Ronda, way more, but struggled more in dealing with a "50 year old fossil who was 50+ pounds lighter" than Ronda ever has in MMA. And that is because that 50 year old fossil was still way more legit competition than any of Ronda's pro opponents, which is why he challenged Lesnar way more than any of Ronda's opponents have.
Brock and Chael has done what to show they are better at grappling in MMA?
Ronda has more submissions, better takedown rates, better takedown variety, and has threaten people on the bottom and on top.
Also, Ronda has way more striking skills than Brock. Ronda finished two girls, one with her hands and one with her knee.
Has Lesnar ever threatened anyone with a knee?
They have gotten takedowns against fighters who are over 10 x more capable of defending TDS in an MMA setting than any of Ronda's opponents for starters. They don't have the same takedown rates as Ronda in MMA because they were going up against athletes of an infinitely higher caliber. However, they 10 x better at the takedowns they relied on most than Ronda was at the takedowns she relied on most. If Sonnen were fighting opponents of Rousey's caliber, he would have gotten as many easy takedowns and finishes. Ditto Lesnar. The takedowns and submissions Sonnen got against guys like Okami, Anderson in the first fight, prime Marquardt and even Brian Stann are worth infinitely more than the takedowns Rousey got against opponents so laughably out of their league. Plus, Sonnen has extensive experience in Greco Roman and Freestyle, so basic understanding of wrestling tells us that it is not even correct to say Ronda has better takedown variety than Sonnen. He didn't use as many kinds of TDs as Ronda did in MMA because he was facing much more legit opposition who could prevent him from doing so. But he had the same variety of TDs and was infinitely better at using those TDs.
And Ronda and Cormier both use their grappling in MMA to dominant effect, but one has to be truly great at MMA grappling and mixing grappling with clinching and striking and the other does not. That is why calling Ronda the Cormier of MMA is actually sort of a real insult to Cormier.