Jack really has shown a lot, but I would not side with the easy portion of your statement (although there is certainly potential for that given JCC Jr's mentality). I think Chavez could trouble him if, and big if it is, Robert Garcia can break through to Junior and get him back in the pressure/body attack mentality he had pre-Sergio. The Chavez Jr. from the Andy Lee fight could make it a tough night for any fighter south of 175, but, unfortunately that fighter is probably forever gone.
I have a feeling if the fight gets made, Jr won't be able to make 168lb so he won't be able to get a title even if he wins.