In the first fight JDS stopped Cain in the first round.
In the second fight Cain stopped JDS in the first round but couldn't put him away. He couldn't put him away for the subsequent four rounds despite JDS not having any real fight left in him due to the shots he took in the first.
JDS has big holes in his game he needs to close. Cain has big holes in his game he needs to close. JDS needs versatility in the event his go-to strategy doesn't work and Cain needs to be able to finish dangerous fighters when he has them in a bad way. It almost cost him a couple times versus Kongo and if JDS could have recovered it was a risk that Cain just needs to take off the table...