Amorim coaching system is flexible and easily predictable. His 3-4-3 formation is not working, making him fix his players in wrong positions. You'll have to have a defensive midfielder in the likes of Nkolo Kante for you to have a formation of that type working fine for you. Manchester United lacks such a good defensive midfielder at the moment. Considering what happened yesterday moral of the clubs fans who has been excusing R. Amorim for all what happened last season has been down for a fourth tier team to ridicule Manchester United.
I think there is no connection between the predictability of the scheme and its effectiveness. For example, tiki-taka once worked, although it was predictable for absolutely everyone. Another question is whether the scheme is suitable for modern conditions and for a specific championship, so far Amorim has not proven that it is. But I am sure he still has a whole season to try. It is unlikely that the management will fire him in the middle of the season, since there is little sense in this - as always, a replacement will have to be found in a hurry + with unclear goals.