I thought Lauren Cohen said something on TD about why she was lying there but now I forget... I think I zoned out just watching Maggie and Sasha's legs throughout that episode. Oofah.
She talks about it around 2:35...viewer call. Basically, Maggie was exhausted from fighting off more walkers than she had expected and that's where she flopped. No real strategy...just where she landed. I can live with that.