Prior Proper Planning Prevents Piss Poor Performance

Oorah!  Was laying down last night taking a rest from my less than active Sun.  Thurs nights battle started going through my head.  Thinking about what I did wrong.  Hoping not to perform the same mistakes next time.  Also hoping to remember what was successful in the first game months ago and use it in the next game.  Several things occurred to me that would've made the game much easier.

Grey Knights deployed first.  Eldar deployed second.  Do you see the mistake that gave Eldar the game that I see?