He just got his blackbelt. I would chalk it up to lack of real life inexperience. JDS is a guy who would rather stand up and fight, and if it went to the ground he would just take the back and throw shots. He could have all that practice time, but if you dont go in a BJJ Tourney or MMA fight and grapple with someone that is going at 100% and trying to take your arm off, you are going to look a little lost when the time does come.
In a sense, im saying that having only 13 seconds total on his back before this fight could have hindered him in the end. He is going to realize he needs his BJJ now and make an effort to actually use it somewhere when he has the chance on his way back to the top.