Frank Shamrock is 35 with many injuries. If you compare his quickness and overall athleticism to his UFC days, he is not half the athlete he used to be.
His cardio is no where near what it used to be
He had many oppurtunities to try and take Cung down and he didn't. If he really wanted to take Cung down he would have tried a lot harder, than that one takedown attempt 30 seconds into the fight...which leads me to believe that ..
4.He is an egomaniac who either wanted to challenge himself, or was so enamored with his own standing ability he thought he would win standing...