When top Clubs like Arsenal, Manchester city, Tottenham and others like Manchester united are all gradually getting down and down the league table, it's not surprising, or won't be of much surprise if Newcastle slips even further down from their current position which is 9.
Liverpool is actually amazing this season, lately, they have been performing incredibly well, and I only hope they got enough current or stamina to keep up with their good performance till the end of this seasons premier league, would be very interesting to see another club entirely different from Manchester city win the title this season.
Liverpool are on fire and very strong as well as ambitious. They don't have many player injuries in this season and this means they usually have best players for choosing squad and substitutions for their matches. It contributes to make their powerful and competitive, ambitious squad and those contributors are important for their success so far. They only temporarily hold the first position but they are strong enough to defend this position till the end.
I saw that after failing in the Champions League, Newcastle's condition was getting worse and it was very difficult for them to perform optimally to win the match. If you look at the number of players who have suffered injuries, it is true, as you said, that it is not surprising that Newcastle are again disappointing. If this does not change, Newcastle's condition will become even more difficult and it is possible that they will be further left behind at the bottom of the standings.
It is predictable because Newcastle United just have their first season in Champions League after some decades. They don't have experience to decentralize their resources for Premier League and Champions League. From coach, staffs to players, they all dont' have this experience and it's no surprise to see they tried hard in Champions League, failed there while they got some consequences for Premier League like low ranking and some player injuries.