Lets not act as if Brock is completely untouchable as a wrestler.
You can go back to his WWE days. Brock and Kurt Angle talked trash about who was the better wrestler. One day they finally decided to find out backstage, and by most every account, Kurt completely tooled Brock. Mind you, this was a roided up 300lbs+ version of Brock against a 220lbs man in Angle.
Lets remember something - Cain is a 2x All-American at Arizona State and a JUCO National Champ. Cain has some outstanding amateur credentials.
Even more, he trains daily at AKA with the likes of Koscheck, Fitch, and more importantly, Daniel Cormier. If you do not know who Daniel Cormier is, I suggest a Google search rather quickly.
From the sound of it, this fight will not happen for quite a while. Which means even if you think Cain is that much below Brock in wrestling, that Cain will be able to train with a huge Olympian like Daniel Cormier for many months.
Do not oversell Brock here while undercutting Cain.
The point of my post was to more point out that Brock isn't 'The Terminator' and he isn't some fighter who cannot be stopped. If you read quite a few posts in this thread, and throughout the internet, alot of people are convinced that since Carwin's unmatched power cannot stop Brock, how can he be?
My simple point is - in MMA, if you have flaws, you are beatable. In Brock's case, he is nowhere close to even being a well rounded fighter. He is a huge brute with great wrestling and little else. Until he becomes more well rounded, he is very vulnerable as a fighter. Shane Carwin proved that.
With the rest of your post - I agree about Sylvia. Not so much Arlovski. If you watched the UFC version of Arlovski throughout those years, he really was a well rounded fighter. He actually had a slick ground game. But now he is convinced he is a fantastic striker, while ignoring the fact he has a matchstick chin.
In any case, the UFC marketed those guys as the top of the sport in the HW division. Within just a couple years, Dana was calling them out as bums and telling the world they had no business in the UFC.
It's the flavor of the week in the UFC. It happens quite often.
Still waiting on Phillipe Nover to become Anderson Silva.