The NFL's Tampa Bay Buccaneers recently played the New England Patriots at Wembley Stadium in London, whose citizenry maintain a cult appreciation for the sport following the decline of its popularity there during the 1990s. Several countries -including Japan, Germany and Mexico - maintain American football leagues. The question remains, though, why football has only achieved nominal popularity around the globe.

Unless a modifying term like "American" or "gridiron" is adopted at home, it will continue to be ridiculed as "illegitimate" football by "real" football (soccer) fans.

2. Identity crisis

Before McDonald's and Coca-Cola, there was the British Empire. Rugby thus retains a strong foothold in countries within the British sphere of influence, where football is seen as a perversion of the sport (though Canada and Australia also have their homegrown derivations).

3. Complexity

The rules and strategies involved in football are exceedingly more complex than most popular world sports today. The harder it is to understand a concept, the harder it is for it to diffuse (see: curling).

4. Cost

With all the safety equipment required - helmets, shoulder and assorted body pads, neck rolls, mouth guards, etc. - it's a lot more expensive to maintain a professional team. This inhibits interest in most developing countries (see: poverty).

5. Commercialization

Excessive stoppage time in football has come to be seen as an instrument for marketing. Though no professional sport is "pure," there is a threshold for what foreign demographics are willing to accept.

6. Monopolization

With the NFL having no major competition from other domestic leagues (see: AFL, XFL, UFL, et. al), efforts to popularize the sport are limited to a single homogenous governing body, which decreases the chance of success - especially with respect to bad business practices (see: NFL Europa).

7. Indoctrination

American children are exposed to football from an early age, and an outlet is provided to them from pee-wee all the way up to high school. Perhaps it's a chicken-or-the-egg argument, but without a system like this, a country will not produce enough competitive athletes (see item 9).

8. Body Mass Index

In 2003, 56 percent of NFL players qualified as obese. With a 31 percent obesity rate among Americans, our talent pool of generously proportioned athletes is, well, generously disproportionate.

9. The Yao Ming Factor

Sports need foreign popularizers in order to succeed globally, but the NFL has a negligible percentage of international players. Most countries don't have the infrastructure to create cultural phenoms, as in the case of Yao Ming and basketball in China.

10. Militarism

Football became widely introduced to foreign countries by American servicemen after World War II. Though this explains why it's more popular in Germany and Japan, this association remains detrimental for any number of reasons.

11. Nationalism

Football fans couldn't really care less if the rest of the world appreciates the sport. Furthermore, they relish the fact that football remains an American idiosyncrasy.