Chelsea lost 4-1 to Manchester United, who secured Champions League qualification at Old Trafford on Thursday night.
Joao Felix got a late consolation strike but only after the Blues collapsed and conceded goals from Casemiro, Anthony Martial, Bruno Fernandes and Marcus Rashford.
Speaking after his eighth defeat in 10 matches as the interim Chelsea manager, Lampard admitted his team aren’t training well enough.
Lampard said: “It’s a question I think as a professional at the top level, will be asked of you in a period of bad form.
“The only way to answer that is to answer with your performance and it starts with how you work and how you train and how you prepare and if I’m honest collectively that’s been the thing that was quite glaringly short.
“There are a lot of reasons for that, that’s not just a dig, that’s because there sometimes are variables. It’s been a tough season, people talk about the squad size, very valid things.
“At the same time, coming in this short period, you can see, when a group is training and it’s really together and pushing and pushing each other, then good things come and you as an individual improve within that.
“At the moment, that momentum is not there, it’s clear.”
The 44-year-old seemed relaxed despite another disappointment against Erik ten Hag’s side who may show a model to develop, adding: “We should look for the future being more positive than what it’s been this season, that’s clear.
“I don’t think it’s one to compare because every situation is different and I think we have to go step by step to look at the big picture rather than just a new manager will change this.
“I’m not taking anything away from the job that Erik has done, or any top manager because you know that is part of it. At the same time, there has to be basics, there has to be fundamentals.
“I remember when ten Hag came at the start of the season, people were talking about his discipline and his fines and his laws and Ronaldo and this situation.
“Set the standard and the tone of how you go forward. That has nothing to do with the individual, that comes after the event.
“I think those things are probably where the club had a positive upturn and then sometimes the players and a good structure will do the rest for you.”