Weren't the Packers competitive before the salary cap was around?
In the age when the Pack were successful, a lot of players had to work regular jobs in the off-season. Kind of like the CFL is still.
You could pay the ENTIRE Canadian league with Aaron Rogers current salary. At any rate, the owners were in the catbird seat back then. They controlled the league with an iron fist, a great example of that was the monumentally shitty retirement and injury deal that the old players from that era had.
The explosion in salaries came about because the players negotiated their fair share of the revenues.