My opinion on Gurley is- and even was back then- that they should have played out the 5 years and then, IF he was still at a high level, franchise him for a 6th season. Would he have held out? Who knows. But in this day and age I am NEVER paying top dollar to a RB after his 7th season. I don't care who it is. The history of the NFL shows that most star RBs begin to fade- and quickly- by year 7. 8 at the latest.
Cam Akers could run for 4,000 yards over the next 3 seasons and I would do nothing other than franchise him for a 5th season. Just my opinion.