Replacement of peacetime leaders with practical experience using wartime criteria combined with the improved doctrine and training adapted to lessons learned would result in improvements in combat efficiency WITHOUT NECESSARILY CHANGING AIRCRAFT.
And that statement, in a nutshell, is what is was all about. Shedding the tactics that didn't work and adapting new ones. Chennault was probably the best example of this. His observations concluded that the best way to combat the Japanese was to minimize the Oscar's maneuverabilty buy using slashing tactics. It was a simple formula but it was revolutionary and it wasn't well received by the bureaucrats back in D.C. Dive, shoot, extend and come back for another round. Boom and Zoom... very simple. It was also a lesson that the Japanese were very slow to adapt to because their aircraft weren't suited for a vertical fight as well as the heavier American fighters. They could climb like hell but high speed diving was likely to turn a Japanese aircraft into a lawn dart.
The problem was that nearly all the world's air forces had trained for horizontal combat, not vertical during the pre-war period. This includes the Americans, the Brits, the Germans and the Japanese. This doctrinal expectation and method of training also affected contemporary European fighter design. The Battle of Britain is a classic example of that style training. Most air combats became turning melees after the bounce.
One can argue that the US and Brit air forces were just as highly trained as the Japanese and they would be correct. But that training is only as good as the framework it is based on. If the framework is faulty, so is the training no matter how good it is, Japanese included. And training does not necessarily equal experience. Experience in air-air combat is far more beneficial than any peacetime classroom or flight training program even when that experience is gained against a third rate opponent. I'ld rather have a 500 hour pilot with 100 hours of combat than a pilot with 500 hours of training and no combat. Many Japanese Army pilots gained extensive combat experience in the skies over China as did a lesser number of IJN pilots. When this experience is added to their extensive and intensive flight training, it can readily be seen how the average Japanese pilot may have been a bit more skilled than their western counterparts. This is not to say that the Japanese were substantially better in every aspect but that they did have certain advantages.
The Japanese specifically designed their aircraft to be the best in horizontal maneuverability. That is what their experience in China and observations from the European conflict taught them. They hadn't as yet encountered a well-trained air force. Many of these lessons came back to haunt them later as their aircraft were rendered less effective when the allies began changing the rules of air combat.
The Brits designed their pre-war fighters as short-ranged interceptors to protect the home islands from attack. And they performed that duty quite well. Unfortunately, few combat-experienced pilots were assigned to the Far East before the start of hostilities. And without the home chain radars to direct the intercept, the Brits were unable to seriously impede the Japanese advance.
The US Army tended to design their aircraft more as bomber interceptors than as fighters so speed and armament were important in their designs. US pre-war carrier fighter design had as much to do with carrier suitability as it did with fighter performance. Robustness was not normally a specific design criteria but more of a reflection of American tendencies to "over-engineer" their aircraft.
One on one, I believe that the average Japanese fighter and pilot
were better than their allied counterparts during the early war period. But that was a fleeting advantage as the allies changed tactics and Japanese losses grew.
Beyond the tactics, there were 2 other crucial elements that allowed allied pilots to take control of the air from the Japanese. The first has already been mentioned... the durability of allied aircraft. Many pilots lived to fight again simply because their aircraft could take battle damage, at times unbelievable damage, and still make it home (or at least close enough to be rescued). Japanese aircraft, once damaged, had a tendency to flame or disintegrate. Had the Japanese aircraft been more durable (or at least better armed), many of their best pilots would have had better chances at survival.
The second of the 2 was communications. Allied air-air and ground-air communications were far superior to anything the Japanese had. Sakai commented on many occasions that it was extremely frustrating to see a Japanese formation about to be bounced and not be able to warn them. The allies also had the benefit of better ground control, especially once radar came into wide-spread use.
Also, one has to be careful when comparing overall kill ratios to determine the effectiveness of any one fighter in fighter-fighter combat unless you remove all non-fighter aircraft from their kill ledger. To do otherwise, presents a very inaccurate picture.
Chez