I dont get the whole "through the legs thing". Everyone faps on when he saves speccys with an outstretched leg but then bags him when it goes through his legs. I'm no keeper but in my understanding you have two choices.

- split legs and hope he tries to pass you or go near post
-keep legs closed and hope you have gadget arms to reach nice and low

He pretty much gambles as to whether the striker will power straight or go to the corners. Or of course there is an option 3
-grow a ****ing tail