The Hammers slipped to a 2-0 defeat at the Cardiff City Stadium, ending their good run of form, of just one defeat in eight matches, which came at the hands of Premier League champions Manchester City.
A sloppy start to both halves against the Bluebirds meant that the Hammers left south Wales without any points, as first Junior Hoilett struck after four minutes, before Victor Camarasa's close-range finish seven minutes into the second half led to Fabianski questioning the mentality of his team.
"I don't know, maybe being in the comfort zone, being in a good position, being safe, relaxes you a bit", the Polish stopper said after the game, as quoted by football.london.
"Some of the games, like for example the last game against Newcastle, we started really well. You could see that the team was up for it."
Despite their shortcomings, the Hammers' goalkeeper insisted that the West Ham squad and manager are determined to improve.
"The manager is very demanding," he added. "He wants us to keep pushing. We have to listen to him and react to his words and to his expectations every single day."
With fears of complacency creeping in, there will be no better test of this than in their next game, which is at home to bottom of the table Huddersfield Town. With the Terriers recording only one win since November, expectations will be high for West Ham to, not only win, but to do so comfortably.
However, whilst Huddersfield are still clinging to slim hopes of survival, they will be desperate to do all they can to take something away from the London Stadium.
Therefore the West Ham manager, players and fans alike will be looking for a professional display in a game where they will be heavy favourites to collect all three points.