Asian Soccer Teams
Asia is a big continent, so it's hard to make sweeping generalizations. I think Zac meant specifically Far East countries like the two Koreas, China, and Japan. So I'll focus on those.
The short answer is that yes, there is a physical gap, and it matters. Yet it probably does not matter as much as many think it does. And it comes with two big qualifiers:
1- it's not about endurance, but height, especially in forwards and defenders.
2- cultural and geographical reasons are probably even more important
The longer answer:
China and Japan certainly underperform in soccer relative to the interest level in the sport and their socioeconomic/infrastructure level.
Asian countries are overrepresented in World Cups wrt the absolute strength of their teams (due to diversity + FIFA voting mechanism), and have produced a grand total of one home-court semifinalist in 2002 following two of the most scandalous refereeing ever seen at the World Cup (and that's saying something, considering the history of the world cup) vs Italy and Spain.
In general, a team like Japan has always massively underperformed vs their home league level and the level of its stars.
The likelihood of Japan winning the 1998 World Cup is not zero -Hidetoshi Nakata (May 1998).
That was a provocative but not outlandish statement at the time. Japan ended its run with a 0-0-3 record, including a 2-1 defeat against Jamaica, a team of amateurs and unemployed young men gathered together by Simoes two years earlier. This is despite the fact that Nakata, Nakayama, Nakamura, and now Kagawa, Honda and Yuto Nagatomo were/are well-established players in European leagues.
They're ostensibly better than any player in US history, yet US has been a regular in the round of 16 and has made appearances in the last 8 in modern times.
I don't buy the argument about stamina.
1- the Asian players in european leagues tend to make stamina and running capabilities a strength of their game (Park, Nagatomo, etc). Asian athletes are very competitive in stamina-heavy disciplines like mid and long distance running, swimming, etc.
2- Asian players who play in their home leagues play less demanding seasons and should be in better physical condition come World Cup times. They're also comfortable in hot and humid climates.
I do buy three other arguments: height/elevation, mindset, and talent pool.
The World Cup is a weird tournament: it's a much shorter and compressed than other competitions, it's played in hot and humid conditions, and national teams do not have time to gel tactically to the level of clubs playing together 9 months every year.
All these factors make set pieces particularly important. Key factors in set pieces:
a) header (and goalkeeping) ability and height, and Asian teams are 4in shorter per player on both ends of the field. Japan has only one player 6' or more. You can't teach height.
b) defensive prowess and roughness, and Asian leagues are among the most defensively relaxed/less tackle-y.
Japan came to the 2014 world cup with an impressive record, dominating its group and upsetting Belgium, with excellent level of play. Japan had a good coach in Zac, well-defined style of play and above-average technique. Japan had a plan.
All plans are good until you get punched in the face, and the plan that works against Asian teams or in friendly matches tends to crumble once you face a taller, rougher, more muscular team motivated by World Cup prospects (for many players, the World Cup is *the* occasion to put themselves on display and get a good contract immediately after).
With their best defensive midfield player, Endo, rapidly declining at 33, there was absolutely no dam against the of the likes of Ivory Coast and Colombia.
Japanese soccer has reached a local maxima in its level of play, favored by its cultural insularity that makes it so that few players go to play in Europe and few european players come to Japan (and none in their prime). That makes Japanese football, with its emphasis on technique and passing, a slightly different sport that does not work against a western style of play. Kakitani, who's the terror of Japanese defenses at home, is a joke of a striker internationally.
The midfield is not a problem as height and physicality matter less than running and technique (and in fact almost all Japanese exports are midfielders or atatcking midfielders), but they do need to get defenders and strikers with international experience, and that's going to be hard because of height.
Finally, soccer is the most popular sport to watch but not necessarily to play in the Far East. Many prospects are geared towards individual sports where they can win gold medals on their own or in a small team: swimming, fencing, archery, where height does not count a lot, or even tennis, where height matters but you just need to field one. The likelihood that Nishikori could have been a good defensive player for the national soccer team is relatively not low. This one factor is even more important in China and Korea.
So what do Far East football teams need to do better?
- Tall and strong prospects that choose to play soccer and not an individual/Olympic sport, especially in goalkeeping, defense and striker positions.
- The above going to play in Europe and absorbing that mindset, and in general to play more against European opponents
There are serious geographical, cultural, and physical barriers to the above, which is why soccer has been extremely popular for 20 years now in the Fa East, but results are lagging.
So physical characteristics are not the factor, but they are factor, and a very significant one.
To people make the rexample of the short-ish Spanish team that won everything for 6 years: that is a really bad surface analogy.
1- Spain's play is completely centered on midfield (where height counts less), where they could run laps around any other team in the world. Unless you have that midfield, and that strong of a home league, you can't play like they do.