I agree with you that Newcastle United is not stable this season unlike the way they were last season, this is because they are playing in the Uefa Champions League, and they are not used to such a situation. I think if they don't qualify for the last 16 of the Uefa Champions League they will be consistent in winning matches in the Premier League. Liverpool might be able to get a point from Manchester City at Etihad Stadium because Manchester City is not at their best form this season.
I believed the Magpies will not make it to the next phase in UCL this season. With their previous performance, they don't stand a chance. The UEFA Champions League competition is one of the major tournament that's drawing the living strength from Newcastle, featuring against elite teams and having absolutely nothing to bother about. Newcastle United will not meet up the standards required of them this season. Eddie Howe and his players are currently struggling, and this might turn out to be a negative decline in the team's performance.