I think a huge amount of England's problems historically has been not having a clear system. There seems to be this idea that if you pick the best players on put them on the pitch, they will perform. But the problem is that certain players (e.g. Sterling) are only great players when they're played in a system that gets the most out of them. They're not the sort of players who are good enough to play in any system and thrive. So Sterling at his best for City is great because of his movement off the ball, making runs for the likes of KDB to pick out. For England, he's often given the ball in front of the defenders and expected to beat them or play a great pass to an attacker, which is not his game. So if you want the winger to do that, you should pick someone else, but Sterling is our best winger so he plays regardless of whether he fits the system, but apparently not good enough to build the system around.
We have the same issue with overrating youngsters at the moment, and seemingly mistaking talented youngsters for world class players. Mount, Foden and Sancho are extremely effective for their clubs, but it's worth mentioning that all are surrounded my experienced professionals at their clubs and play in a system designed to get the most out of them. So it's not surprising that a system that seems to just rely on individuals "making something happen" rather than the system making something happen, that the most eye-catching (if not necessarily effective) player is often Jack Grealish, who basically plays the same role at Villa as the player who everything has to go through.
England really seem to struggle with any cohesive pattern going forward. I had hope in the first game where he picked some controversial options that Southgate was actually picking them based on the system, but it turned out seemingly not. When you see someone like Rashford coming on for Kane, you think "What's the plan?" Are we playing a system where our striker is supposed to hold the ball up and bring in the surrounding attackers (Kane) or are we knocking it over the top for a quick striker to run onto (Rashford).
And the final issue with the current team is the midfield, which is functional at best. Which would be fine if there was the sort of movement from the whole team that you see for City (or Germany tonight), but the lack of a clear pattern of play going forward means you're relying on functional players to pull a bit of magic out of their arse, or more often, the defense to go really directly and really quickly to the attacking four missing out the midfield. And the result is that England look like a shit Liverpool. Just wait til Henderson's inevitable return.