Well they played their best team throughout (which I found odd). I can understand the foot came off the gas though. However Chelsea, Madrid and Watford were all before lockdown and before they won the league. Then you look at the defeats to Arsenal twice so far this season, or Leeds scoring 3 on the opening day etc and it can't all be put down to taking their eye off the abll in lockdown. In fact the only game that fits that criteria is the City game, and in honesty of all the games in question, that one woud have been the one they least wanted to get hammered in.
I mean another point might be, once players step off the treadmill a bit, is it easy to just slip back into the same pace as before? I'd suggest it is pretty difficult.
There was some luck for Villa though I am inclined to agree with Klopp, it is bad defending as much asbad luck. It is defending that is not committed enough, and a team allowing too many shots on goal, and too many attacks. They were unlucky against Villa in that regard, but have been lucky in other games. It's worth adding as well, I watched the last 20 minutes or so, and Villa missed 2 clear 1 on 1's and an open goal. They then seemed to just give up trying to score. I don't think 7 really flattered Villa who could have had more.
Milner and Henderson help, particularly Henderson. Milner must be nearly 35 though and I'm really not convinced he's going to have the legs to resolve this problem. As a starting point they need to get Fabinho, Henderson and Wijnaldum playing together in midfield. That ought to be the priority. Forget Thiago, that is their best midfield 3, particularly in terms of providing protection.
As a final aside, I dont think this means they stop winning games. City got 81 points last season having also been "found out" a bit. Liverpool could easily win the leagye being more inconsistent, and to my mind remain favourites to do so. However the all conquering manner in which they did it has gone. If they persist with the high line, they are going to be involved in a number if games that become something of a lottery.