Honte Lib 4
According to a book by Otake, here is honte, while immediately at a to attack is an overplay allowing White to play at . After White can play at a but Black then has a chance to take the shape point at b.
In the absence of a black pincer stone the same corner sequence is the joseki, almost the invariable continuation.
In this case, is the pro play. When is used to jump out, Black plays and and can then attack with a or b.
Therefore to call the immediate attack an overplay, in the presence of the pincer, requires a comment: that it neglects the pincer stone, rather than being a flawed attack.