Well, they entered the war because the Chinese campaign essentially had ground to a halt with the KMT fortifying and their grip on the countryside tenuous at best.

And their ship design was excellent. The Akagi and Kaga were kind of shit, but then they were battlecruiser/battleship conversions and they were up against the Courageous class which were utter condensed crimes against naval archtiecture in all their forms and the Lexingtons which were pretty good.

And I would argue that their choices over Pearl Harbor reflected their doctrine perfectly; they wanted to force a decisive battle.
By sinking an economically superior enemy's fleet in a shallow harbour unthreatened by land invasion, essentially ensuring that by the time they do sortie for war they will have been at war long enough to make their overwhelming industrial strength obvious. And by doing it during a time of peace without a declared war, ensuring that said superior opponent would be more than willing to never negotiate a favourable peace, based on racist assumptions about democratic societies.
They really did pick the worst ways to execute even their own boneheaded doctrine.