The competition for the top four standings in the EPL is very fierce and always competitive, for now the point gap is one match. I mean when one of the four clubs stumbles it will make them change positions, the points gap has not yet fully formed because four clubs appear consistent. Overall, the biggest factor that plays a role in a team decline in performance is injury, this can never be predicted. If the teams currently competing in the top four can avoid the storm of injuries, I think they can continue to be consistent until January.
The transfer market will always be an opportunity to look for new players and release players who have minimal contribution to the team. I think this approach has been taken from now on. In my opinion, of the four clubs currently in the Champions League zone, one of them will become champions, and at the moment it is not clear yet.
Tottenham would had been the leaders of the league currently but they had a terrible lose and gave Manchester City the opportunity to get to the very top, and one thing about City is that once they get to the top, dropping points becomes an issue cause they'll maintain the top of the table for a very long time, Chelsea might have exposed Tottenham's weak area last week but I don't think it would be possible to beat city this weekend.
However there are several big clubs that still needs to strengthen their team, and luckily for them the winter window is not very far from now, so they have to start now and scout the right players that could help their team get balanced and start doing better than they're doing currently, especially Manchester United that suffered an injury crisis in that area and really needs to be strengthened.