Training a combat pilot takes a lot of time and money. Typically, the more time and money spent on pilot training, the more effective the pilot. That's one reason U.S./NATO airforces had so little trouble with the Serbs and Iraqis.
After Midway, the Japanese really didn't have enough of either (time or money/fuel) to replace the experienced core of naval pilots that it lost. At the same time, American pilots were finally beginning to amass the valuable combat experience and technical expertise that would give them the edge against the Japanese flyers.
The Japanese worked around their mid-to-late war limitations by expanding their Kamikaze program. Kamikaze pilots didn't need to learn dogfighting skills so it took a lot less time (and fuel) to train them. Contrary to ridiculous myth, Kamikaze pilots
were taught how to land.
Although not particularly well-written, this here book does a really good job describing Kamikaze training and the mentality it took to "volunteer" to kill oneself for Japan and the emperor.
http://www.amazon.com/Dangers-Hour-B...5380386&sr=1-1