Chelsea's biggest weakness in Everton draw — neither Kepa nor Koulibaly

Chelsea put in a superior performance against Everton and should have won the game by a big margin. Instead, they drew 2-2.

Joao Felix could be criticised for his poor decision-making in front of goal; Koulibaly deserves stick for his defending against Simms; fans have every right to blame Kepa for both goals the Blues conceded today.

However, it's not the biggest problem at Chelsea. These things happen; players learn on their mistakes and get stronger.

Chelsea's biggest issue in this game and also in the games against Leicester, Dortmund and Leeds that the Blues happened to win, was Potter's negative substitutions.

In all these games, the head coach tried to kill the game off by putting on more defensive players and taking off the offensive ones.

Gallagher came on for Pulisic at the hour's mark against Everton; the same Gallagher was brought on for Felix at half-time of the Leicester game, when Chelsea were 2-1 up.

The same substitution (Gallagher on for Felix) happened after Chelsea took the 2-0 lead against Dortmund; midfielders Zakaria and Gallagher replaced attackers Felix and Sterling in the 68th minute of the Leeds game.

You can see a pattern here: Chelsea get into a winning position and Potter replaces an attacker with a midfielder, going into a more defensive formation.

This approach might work when you're at a smaller team but a big club like Chelsea should be always attack-minded, looking to score instead of trying to not concede.

Hopefully, Potter will learn his lesson from today's draw — until then, his substitutions will remain Chelsea's biggest weakness.