And that may be the factor in this fight. Cain only had to nullify JDS's boxing, with Overeem his facing a wide arsenal of knees and kicks. Either Overeem finishes this or he'll get finished. All up to him imo.
On the same note, in his last fight, Overeem only had to worry about Lesnars TDs, the fight before he only had to worry about Werdums Jitz, his last 2 fights before then, Duffee and Rogers, he didn't have to worry about shit.
Cain is a whole different fighter to anyone he has previously fought. Overeems got cardio, TDs, GnP, striking, heart, level changes and wrestling all to worry about. i may be biased a little towards Cain, my fave HW, but I see Velasquez winning this. Maybe TKO but more likely a decision. Sergie Karitonov was the last dude to KO Overeem, 2007 I think. So yeah, I'd go for Unaminous decision for Cain.