Alistair is a god-made match for Brock's style of fighting. Let’s analyze Alistair’s skills.
He fights in K-1 major tourneys and is successful. He has destroyed Hari and Aerts while losing a controversial decision against Remy Bonjasky.
He has incredibly long limbs that would cause Brock lots of problems and along with speed, that’s a deadly combination. He has the strength of a world class strongman and trains with world champion lifters daily.
He is a completely ripped 261-pounder with not a mere pound of fat. Brock has been said to cut down from 275 but has quite a bit of fat on himself.
If he got rid of that fat he would weigh as much or lighter than Overeem. At that point it becomes a MMArtist v.s a Wrestler. To see who would win, see Kenny Florian vs. Clay Guida.
Overeem’s strength would help him even more because it increases his powerful takedown defense and Brock would get nowhere working for a takedown.
Brock would also have to constantly watch out for one of Overeem’s strongest weapon, the Uberknee. Brock gets hit with one of those and its lights out.
To get a takedown, Brock has to clinch and by clinching he leaves himself open to those knees.
Let’s say Brock could actually get Overeem down; Overeem would use his grand submission game to power into a submission like he did against Mark Hunt and against every other BJJ artist who competed in the tournament that Overeem won.
His main tools are the kimura and the guillotine, which Brock will leave himself open to somewhere in the fight.
People have been criticizing Overeem’s competition and saying that he has not obtained a top ten win since moving to heavyweight, but recently he beat a very credible opponent in Brett Rogers and made many people shut their mouths.
He not only beat Brett, but humiliated him and ended the fight in the first round, dominating of the feet and on the ground.
Overeem can win this fight millions of ways while Brock has limited options. Overeem would be hungry for Brock, and it'll be the first time Brock would get scared.