To be fair, if he's the one to drop out to get Tomori in there (who definitely should be there) then it's a shame but understandable.
Whether any of Coady, Stones or Maguire deserve to be there ahead of him on current form is debatable. But it's never been a case of just selecting the 23 people who played best in the round of games just gone, there needs to be a balance between form and experience, both internationally and at club level.
It's not as if his Villa form has made him undroppable.