In Single-Player mode you start as an untested prospect and fight your way to the top. You will find that regardless of who your opponent is you will be able to absorb an inhuman amount of punishment during standup striking exchanges and the sweeping and passing is too easy when you are grappling.
What this ultimately does is take away any element of danger from the game that exists in a real MMA fight where a match can end suddenly and decisively by a strike or submission. Perks are unlocked throughout Career mode to boost gameplans.