At the time, I ordered the teams crudely based on wins, losses and draws in the tournament, and speculated that only the bottom quarter of that table would see a drop in their rankings over the two-month window during which the tournament was played. I've checked up on things and I was wrong, but still close.
This table contains the data:
|Rk||Pts||Rk||Pts||Rk Gain||Pts Gain|
In total, 6 countries out of 16 (Japan, Australia, China, UAE, Oman and Malaysia) saw a drop in their position on the FIFA tables, with China's at 9 spots being the largest. The most upwardly mobile were champions Iraq (20 spots), Vietnam (18), Indonesia (14) and Thailand (13).
There was an overall gain in FIFA "points" by the contending nations, an obvious consequence of a points system that doesn't award negative points, but only de-values and discards points as older results lose weight in the calculation. But that overall point gain also means that, according to the rankings, the Asian Football Conference, or at least the sixteen countries which competed in the Asian Cup, are an average of 4.25 places "stronger" than before the tournament.
To make the point clearer, imagine two countries playing weekly matches throughout the calendar. Because points are only awarded for wins (and no penalty assessed for losses), if Country A and Country B were to split the matches evenly, they would both rocket up the rankings past nations they have never played.
Unfortunately, I don't have the statistical know-how to do much more than complain, so I'll simply continue to regard the FIFA rankings as something less than the gospel truth.