He just made a stupid mistake.
If you can see the fight again, Cro Cop looks like he is bracing for a body kick. He just miss calculated and underestimated his opponents ability.
He will come back and dominate. Especially since he is getting payed $350,000 a fight, and that is when he loses.
http://www.mmaweekly.com/absolutenm/...=3885&zoneid=3