Lascelles should have been ahead of Jones or Cahill anyway not Maguire (although aye, him too I suppose) - Maguire and Stones are there purely because of how they are on the ball.
He was solid all season where as every other defender picked is almost universally accepted as being shaky throughout the year.
EDIT: Maybe Tarkowski too should have been there, I never seen or heard much about him though.