My point about the victories was if you look at the two units, 8th did almost as well as the 9th even counting their three top aces. 8th FS had 14 aces including three double aces, 9th had 15. According to Osprey, 9th FS claimed 254 victories, 8th FS - 207, and 7th FS - 178.
That's better, but it's not wildly better, and MacGuire and Bong by themselves can make up that difference. Those two guys alone probably put a serious dent in the local IJA air forces. They may not have gotten as many as they claimed but it's a sure bet they waxed more than a few of the experienced Japanese fighter pilots and left some units hollowed out.
Also think of the level of training of the early pilots. Most of those guys had mastered say, a Steerman but were not up to a high performance fighter that complex, probably not really up to flying twin engined aircraft period. They crashed half of their P-40s before they even got to the combat area. Robert DeHaven said he had 14 hours on a P-40 when he went into combat the first time. It was really an unusual character who could step up that steep learning curve for something like a P-38 in 1942.