If a midfielder is leaving, don't they need a midfielder for replacement. Garnacho and Antony are not midfielders even if they will be a big plus to the team but a better midfielder should be kept in mind. Bayern Leverkusen had interest on Florian Wirtz but it is clear now, he will be going to Liverpool.
The idea of ETH brining the same players he used in Ajax and Manchester United is not really make sense to me. They are not the only players who can play his style, he should get other players.
Of course you need to replace a player with another of the same position. But you can only switch a players position if the player is willing and can adapt to that position. Over the years we've seen players switch positions from their natural position just to suit the team. Again, a good coach should be able to groom other players to suit his style of play and not necessarily the players at which he once worked with so I totally agree with you on that aspect.