Was the Japanese Osaka Division really as weak as it was in history?

Not weak at all. It was one of the standing divisions of Japan 17 and the first-class divisions at that time. In terms of armed forces, training, soldiers' quality and combat effectiveness are very strong. Even if it is not as good as the ace troops in Europe and America, it is at least far stronger than the national soldiers at that time. However, the Japanese evaluated its "low combat effectiveness" from the perspective of the Japanese at that time. At that time, the whole of Japan believed in militarism and was very crazy. However, due to the humanistic factors in the area where the soldiers came from, Osaka Division "did not have enough devotion to militarism and loyalty to the emperor", "did not fight unnecessary battles and made unnecessary sacrifices" in the battle, and never engaged in kamikaze attacks or suicide charges.

To put it simply, at that time, most of the Japanese troops were lunatics brainwashed by the emperor, while the Osaka division was normal. In the eyes of other lunatics, these normal people are not crazy enough = weak.