Chelsea’s Premier League title campaign success will be determined by how well they continue to defend under Thomas Tuchel. West Ham showed weaknesses Saturday afternoon and must quickly be eradicated.

The 3-2 loss at London Stadium marks the first time the Blues have conceded more than once this season in any competition. It is also only the third time since Tuchel took over 11 months ago. This should be a cause for concern, considering that in 53 matches, the German has conceded only 29 goals.

Chelsea continues to struggle with proper attacking fluidity, and another subdued substitute performance from Romelu Liukaku served as a reminder of how far Chelsea still has to go in that pursuit. The chances of Chelsea maintaining the pace with Liverpool or Manchester City are dependent on West Ham’s lack of efficient and controlled defense.

This is not the first time Tuchel has been struggling. The 1-1 draw against Manchester United last weekend featured an error by Jorginho which gave Jadon Sáncho his goal. The midweek win at Watford was complicated by Ruben Lampus-Cheek’s loss of possession. This allowed Emmanuel Dennis equalise.

Tuchel stated, “Every loss is just a bump in our road.” “We will not be held back by what we ask, but we must play more accurately, more stable, and make fewer big mistakes.”

Edouard Mendy was the worst culprit against the Hammers. Despite his excellent form in the last year, there was much criticism of the Ballon d’Or structure. However, this was an afternoon that he will never forget.

Chelsea won the first exchanges and led through a 29th minute Thiago Brazil header. Jorginho made a hasty back-pass which put Mendy under pressure. Mendy refused to let Jarrod Bowen close him down and instead made a terrible mess of it, hacking Bowen as the winger ran in front to grab the ball. Manuel Lanzini converted. However, Mason Mount regained the visitors’ advantage with a splendid volley from Hakim Zyech. Chelsea couldn’t keep their composure for the second period.

This is a huge credit to West Ham. They were surprisingly passive in the first period. David Moyes chose a five-man defense that negated Chelsea’s wing-backs, but left them short in the midfield. The second period was a different story. Bowen and Michail Anthony led the charge, making it difficult for Chelsea to make mistakes and ruining their reputations.

Silva won a header from Antonio in the 56th minute, but the ball fell on Vladimir Coufal at the box’s edge. Marcus Alonso was too weak, so Coufal found Bowen and his shot buzzed past Mendy for a level score.

Lukaku was previously introduced to replace the Kai Arertz, but Chelsea were less effective going forward. They managed just one shot on target during the half, after six shots in the first 45 minutes. This was until Arthur Masuaku’s late intervention. It’s hard to argue that he meant it. Masuaku seemed to be using the space left by Antonio to line up a cross, but his delivery was deflected off Loftus-Cheek’s goal and he angled in towards Mendy at the near post.

Mendy was caught flatfooted. Instead of taking a step to the right, he was fully stretched to his right and could not even touch the ball.

Tuchel said that Edu was going through a difficult time. I don’t know the reason, but it seems that he has lost some confidence. We brought him an extremely awkward situation, but his decision-making skills were not the best. While we are not going to blame anyone, we must admit that we made too many critical mistakes in the current situation which cost us three times in a week. The title race is boring at the moment. What is more interesting are the next 90 minutes.

“We must have the right attitude and focus to take care of all the details. At the moment, we are not skilled enough in details. Attention must be paid to the details. It is important to not lose sight of the bigger picture. There is a good chance that we will win this game if we avoid making big mistakes.

Perhaps injuries are becoming more common.

Chelsea was badly missing N’Golo Kante’s ability for predicting danger. West Ham had a head of steam. In his post-match press conference, Tuchel said that he didn’t know when the important midfielder would return. Mateo Kovacic was absent again. With Havertz and Alonso joining, this month will be a tough test of Chelsea’s endurance.

Lukaku was a peripheral player, lacking sharpness and having missed seven matches due to an ankle injury. However, his longest match since Oct. 20 will rekindle the debate about how Chelsea can get him the best. They often look like strangers on the last third with the Belgian.

West Ham has now defeated both Manchester clubs in EFL Cup, as well as Chelsea, Liverpool and Tottenham in the Premier League. They are six points behind Blues who were on the verge of losing their lead at the top.

It will be a close race and although it is only December, Chelsea knows they can’t afford to spend too many afternoons like this.