For me the difference this season, is their quality going forward has dropped off, they are conceding more chances but nobody seems to believe they can score or unsettle them. That's how upsets happen, when teams get their chances against Liverpool(good chances too), sometimes they don't even hit the target, let alone hit it right at the keeper. They are comfortable with a scoreline of 1-0, we aren't(have we ever been?) and I don't see another team like that this season.
They are still one of the fittest, hardest working teams going(tempted hint at German doctors but lets rise above their level), with one of the best presses in Europe and one of the best front 3s(again not as good as last season for me though). What they have added is a resilience that they didn't have before(belief from actually winning something?), they look like they think they are the best in the world(they aren't) and that they can't be beat(helps when you know VAR will step in given the chance) and other teams can't seem to shake that belief when they play them. I do wonder what would have happened if we were awarded that penalty shout at Anfield, or even had the goal ruled out for the handball in the buildup(as they told us should happen when we played Spurs), because they were looking more than a little uncomfortable when we were bossing the opening period.
They will win the PL this season but I don't see them becoming this dominating force everyone fears(nightmare), someone will burst that bubble sooner or later because they aren't quite what they want to believe they are(or want others to). Once that belief is shook, the party will be over for them in my opinion, they'll be a scalp not an underdog, after bigging themselves up for so long.