It is instructive to read this article now and see where these experts were wrong.
Militarily, they were quite correct. Although they ignored Egypt's army (as well as Iraq's), their estimation of the weaknesses of the Arabs besides Jordan were pretty accurate.
They were experts as far as facts on the ground as well as the relative capabilities of the armies. Their failure was in making assumptions as to how the Arab side thinks. Like countless other "experts" before and since, they assume that the Arab side would be logical when deciding whether to attack the Jewish state. They took no consideration of the importance of pride and honor to the Arab mind, which is often the exact opposite of logic.
The idea of a Jewish state in their midst was simply unacceptable, and the thought of defeat as not entertained. Making the assumption that the Arab side thinks the same way as Westerners would when weighing starting a battle is a major, and literally fatal, mistake.
Similar "experts" are still endemic throughout the world, where they predict with confidence that the Arab side will certainly make certain compromises because it makes the most sense. As with these 1947 experts, they almost always know more about current factual circumstances than they do about history, and they fail to draw the proper conclusions from the correct facts.