No, the problem is that you're continually underestimating it, and overestimating Japanese capabilities...<snip>
Anti-aircraft's primary function in this period was to force aircraft to be less effective in their attacks, not to inflict attrition. Fighters were the weapon that could inflict heavy attrition.
And do you have a cite for that, Glenn?
Appendix 10 of Shattered Sword. 13 aircraft shot down, ditched or recovered "out of commission" in the Midway attack are listed for the cause of damage; 10 were by US fighters, 3 by anti-aircraft. That's about 75% damage caused by fighters.
Of the two carrier divisions, Akagi and Kaga's dive bombers were hit by anti-aircraft and little by fighters, while Soryu and Hiryu Kates were heavily hit by the fighters. With the 1st division 1 bomber was shot down by anti-aircraft, 7 were lightly damaged (still operational), one Akagi Val was out of commission. Note that OOC doesn't mean written off, it means that whatever repair was needed was going to take longer than available before the next mission at 1030. That's why Tomonaga's Kate is listed out of commission, but flew a mission at 1pm - they needed to patch a fuel tank, and that required more time. So, the anti-aircraft caused the loss of 1 Val on Kaga (2 in reserve so already replaced) and 1 fighter (could probably be replaced from 6th Ku).
With 2nd division the pattern is much worse, because this was hit by the defending fighters. 18 out of 36 Kates recovered operational (10 on Soryu, 8 with Hiryu). 1 was shot down by AA, the other 17 probably for the most part were damaged or lost to fighters.
The defending fighters were basically finished after the raid - 17 shot down or written off, another 7 or so heavily damaged. Without fighters, the AA simply could not do the job. That's why Henderson Field later was defended by F4F's first and anti-aircraft a distant second.