For me, Iran is kind of remains me of Jamaica (of course, Iran is a better team than Jamaica)--Always have tons of good forwards but the defenders are not up to the standard. What is the reason? My guess that is for soccer culture that encourages creativities (such as African nations), they lack the discipline and team orginazation. For those culture that encourage the other side, they lack creativities (old US, Germany, etc.). Only for some of teams, such Brazil, Argentina, Holland, that can produce both creative attackers and great defenders.