The IJN lost a lot of excellent aircrews at Coral Sea. A number of very minimal changes would save a lot of pilots. If their carriers are still demaged enough to miss midway, those extra veterans could form the core of a much better trained force. They would still be flying inferior machines, but if the opening rounds allow the leading Zero units to downgrade the US fighter defences a lot, the IJN will avoid being massacrated.
The Japanese didn't suffer crippling air crew losses at either Coral Sea or Midway. In a move that was rather surprisingly sensible given a lot of the IJN's attitude toward pilots and aircrew, the Japanese did exactly the same thing as the USN did when a carrier was in serious danger, they packed up the aircrew and sent them off to somewhere safe ASAP. The aircrew went before the Emperor's Portrait.
What gutted the JNAF was the attrition battles of Guadalcanal and the rest of the Solomon Islands/Bismarck Sea campaign. Not that this really mattered.
One of the great overly stated myths of the early days of the Pacific War is just who bloody superior the IJN pilots were. They weren't. They were extremely well trained, many with some level of combat experience (even if it was only flying over a battlefield), but they were not far beyond the pilots of any other combatant state. The RAF and Luftwaffe had pilots with almost as many actual combat hours as some JNAF pilots had flight hours by the time the Pacific War started. The U.S. pilots, especially U.S. carrier pilots were equally trained, if not better trained (USN pre-war policy was to have pilots fly all different types of aircraft, so USN flyers had experience in Scout, Bombing, Torpedo, AND Fighters). This is perhaps best demonstrated by the fact that the early engagements between IJN & USN pilots wound up with the fellow flying the slow tubby blue plane winding up with a positive kill ratio vs the Zero (See Lunstrom's excellent
The First Team for the specific statistics).
There is a rather critical kernel of the truth in the mention of Experienced IJN pilots flying Zeros against the U.S. at Philippine Sea, namely that they were still flying the A6M. Granted it was the A6M3, with a more powerful engine (and slightly less fuel capacity) but it was the same basic aircraft that had flown against Pearl Harbor. It lacked armor, self-sealing tanks, and was woefully under armed. The U.S. was flying the HellCat which had armor, self sealing tanks, a better roll rate, and far heavier armament (even the "up-gunned" version of the A6M still featured two 7.7mm MG).
Much as the JNAF had benefited from the ongoing evolution in aircraft design in late 1941 with the Zero it suffered at Philippine Sea where the evolutionary changes had swept past the A6M. Japan had no hope of winning at Philippine Sea. NONE.
What could have been achieved was a significant reduction in air-to-air victories by the USN. Around 70-80 kills were achieved over Guam, with Hellcat squadrons caught the Japanese taking off early in the battle, and then caught them again at Orote Airfield when trying to land (30 planes were shot down in this debacle) it was the mission where the words "turkey shoot" were actually used to describe the action. Similar losses were suffered by other groups of IJN aircraft as the attempted with withdraw.
The other main source of IJN losses had little or nothing to do with how experienced their escort pilots were. The IJN was gutted attacking the American ships thanks to radar and the 5"/38 DP gun. The radar prevented the Japanese from being able to reach target with any sort of surprise, and radar aimed gunnery (with at least some usage of the Mk 32 VT fuze) was effective beyond even the wildest dreams of any naval planner in 1941.
Japan was crushed at Philippine Sea by technology and superior production capacity.