GSP had already beaten BJ Penn with his grappling by Serra lol. The idea that he shouldn't have grappled Serra and only fought him standing is revisionist history. He had a perceived huge advantage there sure, but he was also perfectly capable of outgrappling him like he'd been doing to everybody post Hughes I when he got armbarred for having that karate first mentality and no world class ground game to compliment it.
As was literally proven in the rematch where he won by outgrappling Serra.
He kept it standing purely because of ego and underestimating Serra. That's not getting caught. That's making dumb mistakes and winning dumb prizes for doing so.
Cain scored 11 TDs, 1 KD, and 13:55 minutes of control in the 2nd fight
http://ufcstats.com/fight-details/02a373f6503b3530
And 2 TDs, 1 KD, and 17:28 minutes of control in the 3rd fight
http://ufcstats.com/fight-details/0bdc4e7ce6687367
Cain beat JDS standing both fights too sure, but it was because he had JDS fearing his grappling which he was significantly imposing on him.