What years did the transition from a primarily running game to primarily passing, begin and end?

There used to be much discussion of how the league was transitioning from a 'run first' game, to much more passing. The theory was that it made the game more exciting to 'air out the ball' on more plays, resulting in more scoring. Teams embraced the changes. But the trend didn't happen overnight. In what year would you say the trend of a higher percentage of pass plays throughout the league begin? In what year would you say the transition had finished evolving into today's game, for the most part? I'm asking this in order to separate historical stats into two major time frames. The first time frame will be when the run game was king. The second time frame will be when the pass game had established itself as king. I don't want to use stats (i.e. points scored) that are too old to help predict the results of today's games.  

Interesting thread and question. 

I guess I'd like to know when the rule changes kicked in. In the past a player could tackle a qb, now you can barely breathe on em. DB's were more physical, used to wipe out any wr going over the middle. Now you must hit them perfectly, not too high, not too low.

There should be a correspondence with the rules changing to the influx of passing, I think?

You can also look at the history of draft picks. Remember when RB's were selected heavily rd 1, now they aren't at all.

Hope this helps.

When coaches realized they could beat teams that way 

Chip Kelly -Oregon 2010/2011 showed you can win and play for a natty with less than 4* recruits.....then in 2015 on pretty much all big time college football teams run the spread/wide open offense...Hence that will translate to the NFL...  

when godsbury and leach systems rule all. 

Kurt Warner & the greatest show on earth figured in some how i reckon. 

Statistically 2001 when teams passed 54.2 % of the time 

The college game changed when the Miami Hurricanes started beating the brakes off of the Huskers and Sooners in the Orange Bowl on a regular basis.  The NFL Changed when the Class of 83 started making playoff and super bowl runs on a regular basis.  Then the NFL started looking for "that guy" to pass them to the Super Bowl every year.  Peyton Manning accelerated the process.

The rule changes are why it's a pass pass pass league ...Has very little to do with talented qbs or style of offenses ..

I would say around 1990. Think Aikman to Irving, Kelly to Reed, Montana to Rice, etc. 

my guess.. it probably started with brady after spygate. then also notice how belicheck is trying again to transition back into the run game. could be wrong

1978 is when they first changed the rules to open up the passing game. Then came Bill Walsh with his west coast offense in 79  with the Niners.

In 1977 the league set a record for low scoring so then decided to open up the passing game, I believe that was the start.

1977 and prior is referred to as the "dead ball era" and 78 and after as the "live ball era" 

TheClaw basically nailed it.  Those rule changes cut way back on the QB manhandling and gave the receivers a lot more freedom.  Here's a list of some HOF QB's, most of whom completed their NFL careers by 1978:

QB   TDs/INTs

Layne 196/243,  Graham 174/135,  Van Brocklin  173/178,  Unitas 293/253,  Blanda 236/277,  Bradshaw 212/210,  Starr 152/138

Tittle 242/248,  Tarkenton 342/266,  Jurgensen 255/189,  Staler 194/222,  Namath 173/220,  Griese 192/172

None of them are even close to a 2/1 ratio.  Yes, some of the modern QBs have suffered serious injuries, but by comparison those rule changes have certainly boosted their stats vs. the old timers.

Claw and Dogbite, good stuff. 

There were more rule changes made in recent times. 2 specifically involved Tom Brady.

1. The Tuck Rule.

2. When he tore his acl in week 1 or 2 vs the Chiefs. The safety(forget his name) blitzed and went low, it wasn't even intentional looking. But ever since that injury, no one can blitz the qb low anymore. Nor hit em high either.

When they figured out runningbacks were overrated and drafting runningbacks in the 1st round was a waste of a pick.