Flick can do better, but it's not like he's operating in ideal circumstances. Team played really well last season. Then a lot of other teams made investments including Real Madrid. Now investments don't always equal to better performances(see Liverpool so far), but the squad depth RM have is light years ahead of ours.
We lost our best CB who was good, but not spectacular. We signed a GK who was upgrade, but didn't play tonight and, Rashford on loan and Roony.
And everyone knew that we needed a LB/RB, #9 and arguably a CB as well. Almost everyone in this forum agreed on that, but finances wouldn't allow it. I believe I said it a week ago. There's only so much you can extract from your academy and what you already have in the squad. At some point you need to make some big investments at key positions when you need it, and we needed it and couldn't do it.
Although the season is long. We were in a worse situation last winter. We'll see what happens.