First 2 matches evaluation from my point of view.
Ten Hag got it tactically wrong with Eriksen as the false 9. Why? A false nine shall has ability and pace to run away from the defend. Which Eriksen doesn't has. Eriksen best ability is the playmaker and creative part of the game.
Second game. Ten Hag admit his mistake. Learn and drop Eriksen down as one of the cm player. But De Gea first goal mistake and too risky pass to Eriksen with a Brentford player right behind is back. Play long when you have too. Don't get stuck on always play from the deep. Choose the way of play when its most benefit. Example if you have to play long to counter, you do it. Why always trough midfield? Same as the goalkeeper.
So Brentford 2 goals up and with the home growd and rising of confidence.
And in the end. Ten Hag shall focus both on the defensive too. Not only focus and build and attack. A team hard to beat and hard to score against are really big big factors , on the patch to succeed. If he only focus on the build and attack, but lesser focus on the defend. Average or weak in the defend. Then it will be a really long way to go.
A rock solid, strong and good organisation in the defend + adding with top flair, creative and attack skill. Like the France 98/02 and Arsenal invisible and Inter treble season with world class CB in Lucio. Are the way to go. Conte and Spurs are trying to create and build towards those 2 factors too. Spurs and Conte with a strong and good defend organisation + adding and spice it with top and really good attacking player in Son, Kane and Kuvuleski.
And from that point of view. I think Malacia and Bissaka is better than Shaw and Dalot in the defend. Shall start overe those 2. United shall have enough creative ability further up the pitch in Eriksen, Bruno, Rashford and Sancho + CF. And Malacia and Bissaka can make good run forward with the ball too. Beside theirs better defensive ability than Shaw and Dalot.
At this moment. I think and believe United best line up is. Most rock solid and hard to score against is:
Bissaka - Varane/Bailly - Martinez - Malacia .
I would look forward to see that back line together.