Understanding the structure and context

The teams that are bad for long stretches have terrible owners.

The league enforces balance, much more so than in European football leagues.. The teams that finish the worst get to draft first so have access to the best players. There is a salary cap which prevents one team from buying all the best players. And on top of that for many years there was "parity" scheduling which meant that the teams with the best record from the previous season would play tougher schedules than teams with worse records.

The problem with the bad NFL owners is they often try to run the teams themselves, and they don't know what they are doing and/or are extraordinarily cheap. If say, Al Davis (ex-Raiders owner) gets a high draft pick and every year he uses it (or orders his GM to use it) on a speedy wide receiver with questionable hands and a sketchy off-field history, then the Raiders will be bad every year. Mike Brown (Bengals owner) is another one. Daniel Snyder of the Redskins. Jerry Jones of the Cowboys.


To answer your other question, there is no "pure" way of playing football. However, playing styles are often related to the conditions where the teams play. For example, in cold weather passing is difficult. Teams from those areas are typically built on fierce defense and good running backs. For example, the Eagles, Vikings, Bears, Steelers, Packers are all known for their defense.

In contrast, teams from nice temperate climates or perhaps who play in domes are known for high scoring passing offenses. The 49'ers or the Chargers are good examples.

 

Here is a post-draft trade that changed two franchises:
New York Giants Get: Ole Miss quarterback Eli Manning, the No. 1 overall selection in the 2004 draft.

San Diego Chargers Get: North Carolina State quarterback Philip Rivers, the No. 5 overall selection in the 2004 draft. In addition, San Diego received the Giants' third-round pick in 2004 (used on kicker Nate Kaeding, No. 65 overall) and Giants' first- and fifth-round picks in 2005 (first-rounder used on Shawne Merriman, No. 12 overall; fifth-rounder traded to Tampa Bay, who traded pick to St. Louis Rams).

Why: Manning was the clear-cut No. 1 player in the '04 draft, but his father, Archie Manning, made it publicly known that Eli had no intentions to play in San Diego, where the Chargers held the No. 1 pick. Instead of taking Manning and forcing his hand, the Chargers drafted him and later shipped him to New York for Rivers and a ransom of picks.

Why? You can draft a player but he doesn't have to sign for you. If the draft choice doesn't sign by the next Draft, he is up for grabs again!

The great John Elway refused to play for the (then) Baltimore Colts and went off to play baseball for a few years. When the Broncos got his rights in the next Draft, he found the will to play football again. The same thing happened with Bo Jackson and Tampa in 1986. When he refused to sign for Tampa, the Raiders drafted him with their last Draft choice the next year. Too bad his career was cut short.

Here are some examples:
http://www.complex.com/sports/2009/09/money-talks-bs-walks-a-history-of-nfl-rookie-holdouts

 

Is the salary cap a percentage of turnover or the same everywhere?

 

We're Americans. We don't know what "turnover" is. We call it "revenue."

Seriously though, The salary cap is a flat figure for that is the same for every NFL team. It is currently set to $120 million for the next season.

 

Teams share general revenue up to a point.
If an individual team can sell corporate sponsorships or stadium naming rights, it goes right into their pockets.

There are teams that can't sell out tickets to their home games. If the stadium isn't sold out two days prior to kickoff, a television blackout occurs in the home team's area, according to the television contract with the NFL.

 

I've always admired the fact that the sport has this kind of socialist approach, helping the poor and needy and putting the brakes on the rich to stop them taking over.

I really wish English football followed a similar practice.