they are on the same level as boxers. Diaz isnt as technical but he has a better chin, stamina, and when mcgregor gets hit he wears down fast. Mcrgegor has a better jab and straight left and footwork. Both are 30% amatuer boxers.
McClown, like most MMA fighters, has a glass jaw. Any decent boxer -- including Olympic boxers making their pro debut -- would shatter that fragile mandible.