Would you keep an under achieving employee for more that 7 or 8 years? Would you pay a guy from a College instead of a University top money? If he does not produce when you hire him, do you still want to keep him hoping he will eventually succeed? Dak is here for a year or two, I don't know, but if they extend him...well, I guess the JJ does not like change and Dak is getting older and regressing, and he is about a 6-7 tier QB injury prone lately.
If Dak demands an extension and JJ bends over again, good luck Cowboys.