What if Minoru Genda, the First Naval Air Fleet CO of the Nagumo Force at Midway, was in good health and commanding the airoperations for the carrierforce of Vice Admiral Chuichi Nagumo during the Midway battle? In his place Vice Admiral Nagumo himself would be the one who was temporarily off duty for some fever, or illness, being temporarily replaced by the commanding officer of the 2nd Carrier Taskforce, Rear Admiral Tamon Yamaguchi.
Historically Genda was ill during the battle itslef and was replaced by a junior officer as acting airgroupleader. Vice Admiral Nagumo tended not to intervene in airoperations himself, leaving such things to his subordinates, who were more or less free to do as they pleased. Yamaguchi was justy the opposite and a strong suporter of naval airpower himself, where Nagumo was actually a torpedo specialist, used to command destroyerssquadrons in action.
So Genda, the most experienced commander of the Naval Air Fleet, was normally free to act on his own innitiative under Nagumo and was definetely the most skilled person to do so in the IJN.