There's little doubt that the NFL has seen a rise in popularity over the past several decades, perching it atop the American sports landscape.

But as the game has grown, rules have changed. Much of the emphasis has been on player safety, with quarterbacks and other offensive players increasingly afforded greater protection.

Reaction to the changes has been mixed. To some, it's part of a natural evolution toward a faster-paced, speed-based game. To others, football has shifted away from its roots as a physical sport.

Given the chance to be NFL commissioner for a day, which rule would you change?

That's the question we asked several Pro Football Hall of Famers at the Hall's inaugural Fan Fest in Cleveland in May. From stars of the 1960s to players who earned their gold jackets playing a more modern version of football, there was no shortage of opinions about how to change the game -- even some you wouldn't expect.

"Well, I'd put the head slap back in," former defensive lineman Carl Eller cracked.

Eller, a member of the Minnesota Vikings' famed "Purple People Eaters" of the early 1970s, took a more serious note when he offered a popular commentary about the modern NFL: It's becoming too much of an offensive game.

Here are more proposed rule changes and thoughts from Hall of Famers in our latest NFL Nation Says:

Contributing: Coley Harvey, Pat McManamon and Michael C. Wright.