And, once we developed appropriate ACM to counter their maneuverability, they began to lose their most successful, experienced pilots. And that caused their training program to be toilet fodder.
I read the AAR for the Midway battle, the USMC pilots were basically "inexperienced" right out of the Cadets. Some of the Buffalo pilots claimed the Zero was doing 450mph or faster, while others climbing endless without slowing down. The only thing noted was the Japanese Zeros were paper thin.
In the first month the USMC in January 1942 pushed out more pilots then the Japanese did in ALL of 1942 and some of 1943. Our veteran pilots were rotated out to train pilots, while the Japanese didn't start this until 1944 - FAR after the 1942/1943 battles that torn apart the Japanese.
The Japanese were able to crank out pilots in 1944, however with most of their experienced pilots dead - it was a lost cause, Australian and New Zealand pilots were working well with American counterparts, enough the P-40 and P-39 had a decent kill ratio against the Japanese (I didn't say it was flawless).
New Aircrafts like the P-38G and P-47 (although only a few were in service compared to 38s due to range) made a hell of a difference as well.
Japanese had a first rate airforce, Guadalcanal killed it forcing the pilots to fly over 8 hours - then combat, where the Americans took 15 minutes to up and were fresh. Even though the Japanese had "Aces" the Americans had time on their hands, it basically tipped the balance.