The Nazgul. Men?

[Kuruharan]

Gothmog's "assumption of command" also sounds exaggerated here. He did nothing more than "fling" the troops "into the fray."

That had been pretty much the brilliant tactics of that vaunted soldier the Witch-king.

Also, I don't think Sauron ever imagined the Witch-King falling

He probably did not expect it. However, considering how obsessively he prepared for this war, I'd be surprised if the thought had not occurred to him and if he had failed to plan accordingly. He knew that there was this irritating prophesy of doom hanging over the head of his most feared minion.