Breaking open the front of a phalanx

[Parallel Pain]

You're forgetting they threw out the shield by the late middle ages.

And also flanking is not so easy in real life when 1/4 of your commands (or 1/2 for cavalry) either wouldn't reach the men or they wouldn't obey it, going off chasing and plundering.

And that the pike square of the late medieval/renaissance era is different from the phalanx (per Watchman) with one of the difference being it could be interlaced with close-melee troops wielding halberds and swords.