I agree, the Japanese are overrated. They were only able to perform the rampage they did OTL because they destroyed the US and British Pacific fleets.Not really. If anything it was behind the U.S. and RN overall. As an example they had a REALLY screwy perspective on anti-aircraft defense, while the American and British escorts were a critical part of the defenses of the task force, the IJN didn't do things that way. The carriers were seen as being their own best defense, using their own AAA mounts (which were markedly inferior to the U.S. 5"/38).
What the IJN was able to do, which the U.S. and UK couldn't, was concentrate all their carriers into a single striking force, the Kido Butai. That gave them the six decks needed to perform the Pearl Harbor operation. The Japanese could do that because they only had to cover half the Pacific. The USN had two Full Oceans and a Sea/Gulf to deal with, the RN , three Oceans and a Sea.