Also, an unconfirmed report has it that one factor was the fact that the YF-23 had its internal AAMs "stacked" in its bays, while the YF-22's missiles each had a bay to themselves; this meant that, on the YF-23, a malfunction in one launcher might prevent the launch of another missile in the same bay.
Although I don't know why Hildegard disregards the YF-22's manouverability with the following qualifying statement ("even though this was not a mandatory USAF requirement"). I'm sure it's not his words and he just copied and pasted it from somewhere, but I can't understand what the point is of saying it. Sure the thrust vectoring isn't a requirement, but the increased manouverability is certainly a nice bonus.
I could probably show some pictures of accidents with the YF-23 as well....if it had been chosen instead of the YF-22.