The warning sign was there last season when no team below the "big six" even had a positive goal difference. The season before, seven teams had a positive goal difference. The campaign before that, when Leicester won the league, it was eight. The fear is it could again settle on six - there are currently 10 - because in terms of results, this season has reinforced the dominance and lessened the variables even further.
On Monday, there was another game at Stamford Bridge. Crystal Palace had drawn level at 1-1 and it briefly felt like the game was in the balance. Except Chelsea head coach Maurizio Sarri summoned arguably the league's best player Eden Hazard and Mateo Kovacic, on loan from Real Madrid, from the bench. Soon it was 3-1 and game over.
It meant that Chelsea, like Manchester City and Liverpool, remain unbeaten after 11 games. Those three teams alone have 83 points while the bottom half of the league (10 teams) have just 82 at the time of writing. It is also the first time three teams can boast an unbeaten record at this stage of the season since the Premier League began and the fact is that the 14 teams below the "big six" are struggling to take any points from them.
United are the exceptions, having lost to Brighton and West Ham and drawn at home to Wolves, but that owes much to their own catastrophic failures. They are the exceptions that prove the rule, even if there are signs that they are improving - they worked the strength of their bench to beat Bournemouth last weekend.
So far, Liverpool have won all seven of their matches against the other 14. Chelsea are unbeaten against teams from the other 14 - winning seven. Arsenal also have seven wins out of eight, with one draw. Tottenham lost to Watford but have also won seven of eight.
City are not just beating the others but destroying them - Huddersfield 6-1, Cardiff City 5-0, Burnley 5-0 and now Southampton 6-1. They have won seven and drawn one.
It means that of the 48 matches so far between the "big six" and the other 14, the big teams have won 41, drawn four and lost just three.
It also demolishes the arguments put forward by some of the "big six" that the league is now more of a level playing field because of the money from the broadcast deals made available to every club.
The school of thought is that even the smaller clubs can pay £30 million for a player and wages to match while their greater financial muscle means they can resist offers from the "big six" for their top talent.
That argument has already been behind the drive by the "big six" to renegotiate the distribution of broadcast money from the overseas deals - so they can take a greater share. It is also implicitly behind them - apart maybe from Spurs - being allowed to be associated with a breakaway European Super League. Chief executives at other Premier League clubs note the "big six" often have their side meetings or huddles.
It had been hoped that Leicester's success would break the mould. It only led to it being reset, with the bigger clubs not only signing better players but hiring better managers with better tactics. They had become complacent. Now they are hammering home their advantage.
Since that Burnley game at Stamford Bridge in 2017, there have been only two upsets at the homes of the "big six" - Bournemouth at Chelsea and West Brom at United. Will there be any this season? Sadly for a competition which claims "any team can beat any team", it would be no surprise if it did not happen.
The Premier League will still argue it is competitive but can only spin it on games between the "big six" - although City are now threatening that. But that is another argument.
