Theory in Question:

Depending on the position, mental state of mind, an unnoticeable type of play that appears balls out yet is 85-100% geared on remaining healthy/avoiding injury.
Making it closer than it has ever been for a player to ignore his age and continue his career well past the likeliest age his position normally requires retirement.
In essence you now see players playing past that "call it quits age" which enables them to play where they want.  Not in a guaranteed condition, but they do increase their odds of eventually making it to desired team or making it to a team with the greatest chances of winning them a ring for their finger.
They have realized they can take whole years, maybe even 2 off for injuries.  Rehab very strong, live an extremely healthy life with food & avoiding false chemicals that age a human body.  Again, there are many more practices that have been at the front of human understanding and an insatiable search for the fountain of youth.  Many think Ponce de Leone was at the heart of this desire, yet that seems to only be a myth.
It is far from a myth that millions & more are still searching for this fictitious gulp of liquid that halts aging by the human body.
However, it is possible to the slow the progression.  And this practice taking place by more each year has switched the power of the....struggle/competition/see who blinks first....between the players association and the Owners.
The Owners must come up with something to bring back the closest equableness by teams that still has exceptional fan loyalty & a competitive fieriness' for victory & a trip to the playoffs.
Right now the cream rising to the top each year has a very similar look. Same colors, names, cities, teams, etc...
The rollover/turnover of NFL teams is not happening as much as it used to.  Maybe the NFL has become so strong they needn't worry about fans of losing teams not showing up to home games. Or if they do, they are alone in 8 sections of emptiness & they wear a paper grocer bag on their head.
The gambling/fantasy aspect of the NFL has won out. Very similar to when Nixon allowed Insurance Companies to create another form of society that has it's own economic existence, & forces more members in each year.  Try see a doctor without being insured.  Say you are depressed, a condition you suffered previously and were cured or set back on track by taking Prozac for 2-3 months.
Go to a walk-in clinic and say your piece=want to see a Doc, depressed & it was cured before by using Prozac for 3 months.
They'll ask if you are insured. "No." Okay, that will cost you $300.00 to see the Doc, and most likely he/she won't prescribe an anti-depressant.  "What if I was insured?"  Well, that depends.  But ball park it will cost you $50.00 & you'll probably get what you want. 
You are favored with insurance and you are screwed without it no matter if you can afford it or not. 
The point of all this is the oldest story in the book.  The money rotates to those that have it.  Trickle down theory.  That was a blind fold creating belief among those oppressed; one of the greatest ever.  If you examine close enough, you will see the same business theory/program operates within the NFL.
Even though I enjoy the NFL sometimes.  I would love nothing more then to see a 5-8 year period of these FB players lose the league.  No paychecks for 8 years. Watch them wonder around penniless and then hear all of the old clichés about how N#$gg%^rs are discriminated against.