Yes Mason Mount needed some time to adapt to Ten Hag's style of play, which is natural considering he needs support and I think what is really important is the emotional connection between the players.
Pre season games are pre season games; they do not mean anything; and they are only used to build up each individual players fitness; build chemistry between players and prepare the team tactics ahead of the new season. I believe Mason Mount and the other guys performance will improve as the pre season games kick in.
Important season ahead for Manchester United