You're right, Newcastle can't be called an average team. They've been consistent in the Premier League for quite a while now, but this doesn't guarantee this season Newcastle will be at the high level like last season. Their stats against Liverpool might makes you feel bad as they are are on 7th Premier League games without a win against Liverpool. But, I'll be happy if this match against Liverpool will be tough because Newcastle have the strength and form to punish them. At the same time, Liverpool still have enough quality to edge it if they stay focused. I'll be pick Liverpool anyway.
I do not know your bases of judgement for an average team and one which is not but for me any team who is not consistently at the top five by the end of the season is on which I consider an average team and seeing Newcastle I doubt they have been consistent around this spots in the last five seasons, I stand to be corrected though. Secondly I do consider team depth as another checker for average team and with Newcastle we agree that they have only a very few to players of which the rest are mostly average so except they keep improving, that is where I see them for now.