Liverpool suffered on numerous fronts at the Etihad. There were already questions before Sadio Mane's contentious red card, but the inability to keep the score respectable show up some defensive weakness in a harsher light.
Positives
Mane can still play in the Champions League, at least. The Reds won't be the only team to lose heavily at the Etihad. Anything more than that would be an expression of simpleton serenity.
Negatives
It's not the first time the Reds will be let down defensively this season. If the forwards have off days and don't take chances, games are almost guaranteed to end badly.
Manager rating out of 10
3 -- Poor defensive selections gave City no respect and Liverpool paid the price. Jurgen Klopp can argue all he likes about the red card but his team's inability to be professional and achieve damage limitation exposed a tactical naivety. The withdrawal of Mohammed Salah was virtually surrender, so he couldn't expect his players to do anything else.
Player ratings (1-10; 10=best; players introduced after 70 minutes get no rating)
GK Simon Mignolet, 6 -- Can't be blamed for any of the goals. Exposed time and again and if anything stopped the score from being hugely embarrassing. Thanks to him, it was just fairly embarrassing.
DF Trent Alexander-Arnold, 3 -- Out of his depth in a major way, so perhaps people can now rein in their expectations of what is after all a youngster. Not keeping tight on Kevin De Bruyne before the Belgian crossed for second goal was just one of numerous errors. Received no protection whatsoever, but that's an easy cop-out.
DF Joel Matip, 4 -- Not the worst defender on show; nevertheless, was poor throughout. Failed to spot when his partner was almost asleep which means he'll avoid most of the criticism, but still a part of the general malaise at the back.
DF Ragnar Klavan, 3 -- Trusted by his manager ahead of Dejan Lovren, which wasn't paid back. Will be forgiven largely because he shouldn't be playing at this level against potentially lethal opposition. That blame lies with Klopp and the club's owners.
DF Alberto Moreno, 6 -- Actually wasn't too bad. For a player who's often first to feel the wrath of supporters, it's only fair to point out few of Liverpool's problems stemmed from him. One or two good moments in the first half when it was eleven versus eleven. It was all downhill and academic after that.
MF Jordan Henderson, 5 -- Usual work-rate can't mask a lack of ideas, but hardly protected his centre-halves either. Bad day all round.
MF Emre Can, 4 -- Not at his best even in the first half. Became a makeshift centre-back second half but is often reckless with touch, aggression and positioning. It's easy to get away with that in midfield, not as the last line of defence.
MF Georginio Wijnaldum, 3 -- Largely invisible, still a thorny problem between good home form and irrelevant away performances. Lucky to last 58 minutes, despite his team being reduced to 10 men. Might be cruel but some fans feel Liverpool are always down to 10 men away from home.
FW Sadio Mane, 5 -- Clearly a threat to City in opening 35 minutes, until red-carded in the incident which irrevocably changed the game. Slightly unfortunate, although the challenge was dangerous, he had to try to reach a 50-50 ball. Not relevant now anyway, as everyone should just wish Ederson all the best.
FW Mohammed Salah, 6 -- The most dangerous Liverpool player, with another frustrating lack of end product. His half-time substitution was clearly Klopp's way of preparing for Liverpool's next game, because only Salah could possibly have tested City by that stage.
FW Roberto Firmino, 4 -- Not at his best, and incapable of testing City on his own in the second half. His work-rate was obviously considered vital, but when Liverpool couldn't even limit the damage he was brought off to rest for the Champions League.
Substitutes
MF Alex Oxlade Chamberlain, 5 -- Incredibly difficult circumstances for a debut. Had one or two good moments but was largely anonymous and didn't keep possession very well when it was vital to do so.
MF James Milner, 5 -- Also tasked with helping to see out the game, gave his former club one or two anxious moments but couldn't help stem the tide flowing the other way.
FW Dominic Solanke, 5 -- Brought on to save the legs of one of Klopp's favourites, he managed one or two good moments despite being painfully isolated at times.