Since the forward pass was illegal when the NFL originated, let's focus on the rules that have changed the game as we know it today. These are the top five significant NFL rule changes in history. Well, at least in modern history.

Salary Cap

One reason the NFL reigns supreme over the other leagues is its unpredictability. Making the playoffs in consecutive seasons is an amazing accomplishment, especially when all 32 teams must construct their roster following the salary cap. The salary cap may change annually, making it easier for teams to maintain a championship roster. But franchises must make difficult decisions every year.

Playoff Expansion

The real reason for playoff expansion is that it brings in more revenue for the league. Regular season games are the highest-rated TV shows in a calendar year, so you know networks want as much playoff action as possible. A few years ago, the NFL increased the playoffs teams in each conference from six to seven, only awarding a bye week to the squad that finishes first in the conference.

This decision makes teams fight hard for the number one seed to get an extra week of rest, and it allows middle-of-the-road teams to fight and claw for that seventh spot. There haven't been any upsets from the seven-seeds yet, but you know it will inevitably happen.

Two-Point

The two-point conversion is there to give hope to teams who are fighting from behind. Additionally, it's there for coaches to put their cards on the table and go for the win instead of playing for overtime. It's still perplexing, particularly when they moved the extra point back, that more teams don't go for two when it's unnecessary. But let us count our blessings coaches realized that doing it when down 14 is the correct analytical decision.

Illegal Contact

Of all the penalties that changed the style of the game, the illegal contact rule is the most influential—not being able to initiate contact with a receiver after five yards made the passing game much easier.

The rule was in the rulebook in the 1970s, but referees rarely blew their whistle for it. Who knows what the league would look like if the Patriots didn't bully Peyton Manning in the 2003 AFC Championship games?

Instant Replay

Think about controversial plays that shaped this game forever and how things would have changed if instant replay had been available. Without instant replay correcting major and apparent errors by the officials, we might have different champions. The system still has flaws, but it keeps things in order, preventing catastrophic results.

The top five most significant NFL rule changes in history could vary based on whom you ask. But there's no doubting that these have and will continue to play a pivotal role. Pregame is here for you to offer expert betting tips to give you the advantage on NFL Sunday. Show off your skills and join any of our free contests while you duke it out with people's picks across the country.