頭の回転 vs Just 頭 Alone


小回りの利く機動が得意しかし頭の回転が やや鈍い

In this line from Attack on Titan, how is the nuance of 頭の回転がやや鈍い different
than just saying something like Atama ga yaya nibui?




頭の回転の速さ is mainly about responsiveness, whereas 頭の良さ is about intelligence in
general.

頭の回転が速い人 refers to someone who is ready-witted, is quick to respond to jokes,
is good at staying logical even in a fast argument, etc. A professional
comedian or a TV host is a typical example. 頭の回転が遅い人 (or 頭の回転が鈍い人) is the
opposite of it, so it typically refers to someone who is slow to understand
someone's commands/jokes or make resourceful decisions in response to a
trouble.

頭がいい人 encompasses 頭の回転が速い人, but it's someone who is intelligent and smart in
general. It can refer to someone who is knowledgeable, who is good at
memorizing things, who writes perfect papers even if it takes some time, and
so on. Its antonym is 頭が悪い人.

頭が鈍い is not a very common expression, but since 鈍い on its own denotes slowness
and insensitiveness, it sounds to me like somewhere between 頭が悪い and 頭の回転が遅い.

