A long overdue (on my part) mystery solved. But in case, you haven't seen it yet, here it is:
I guess nothing could've been worse than saying Ted could never get to the bottom of it. That was like saying Marshall just happened to forget one of the slaps. It was a mystery, like many on HIMYM, that we we eager to see solved. I guess they gave us some closure with this, but they could have done better.