I can see your point, and agree that there have been too many defensive errors, and very early in the game at that, which immediately gives the oppo a confidence boost, and the freedom to risk a bit more.
But the first point you make is the salient one. We should be set up to be solid from the start. Three minutes in against Villa, yes, Grealish ran past Odoi for a one-on-one with the keeper. On re-watching the goal it looks as if Grealish is central about 7 or 8 yards outside our box. I can't be sure as I didn't really think about it at the time, but I don't recall a Fulham midfielder within 10 yards of him. There was certainly no one in front of him. 3 minutes into the game for God's sake, and we are giving a player rated very highly by many, that much space in front of our back 4.
So yes, I want to see us protect that space right from the start. I want to see a defensive set-up that means if one of the full-backs does get forward, the shape of the team adjusts so we just don't leave a gaping hole down that side of the pitch. That can be for the remaining 3 defenders adjusting their positions, or indeed a midfielder holding back or even moving across. But I don't see us doing anything and both full-backs are being caught wrong side of their counterpart who has acres of space in front of him.
So it's all very well Parker saying our defending has not been good enough, but he has to set the team up "to be hard to beat". We have a better chance of winning games if we are 0-0 rather than suffering a 3 goal deficit which has happened in all 4 games so far. Let's start tomorrow.