I disagree that it has anything to do with man vs. boy.
The phrase "play like a girl" is a reaction to "throw like a girl" and "fight like a girl", which meant to do those things in a less than effective way. Now that phrase is being redefined as a statement that girls can do things just fine and doing something like a girl does not mean doing it badly.
The phrase "play like a girl" is a reaction to "throw like a girl" and "fight like a girl", which meant to do those things in a less than effective way. Now that phrase is being redefined as a statement that girls can do things just fine and doing something like a girl does not mean doing it badly.