Chelsea boss Graham Potter believes the club's problems date back to a preseason which the senior players described as the worst they have known.
Chelsea travelled the United States last summer, beating Club America in Las Vegas before flying to the east coast where they lost on penalties to Charlotte FC and were then thrashed 4-0 by Arsenal in the Florida Cup.
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Their final outing came in a 3-1 against Udinese in Italy but just a few days later, then head coach Thomas Tuchel described the entire schedule as "tiring" and "exhausting", believing it left his squad ill-prepared for the new season.
There were also tensions between Tuchel and the new owners, Todd Boehly and Clearlake Capital, over transfer targets and his management which eventually led to the German's sacking in early September.
Potter replaced Tuchel but has overseen just two wins in 14 games across all competitions, a run which continued with last weekend's 1-0 home defeat to managerless Southampton which some fans greeted with boos and calls for Potter to be sacked.
After the club spent £600 million in two transfer windows leaving Chelsea with a bloated squad, Potter launched an impassioned defence of his position, highlighting various issues including some he claimed to have inherited.
"It is really tough, my quote is 'it is probably the toughest job in football', [I said] that was a few weeks ago," Potter said.
"There are a lot of factors in that. Again, if you just take the season, a sub-optimal preseason. Speaking to a couple of the experienced guys, they thought it was the worst pre-season they've had for different reasons. That's not to blame anybody. For different reasons, that happened.
"I don't think I want to speak about [the reasons]. It is more just organisationally, for different reasons the tour didn't work as well as they would have liked etc etc. I wasn't there, I can't say.
"But that's a thing. Then old players left, new players come in, manager change, I turn up in the middle of a Champions league Saturday-Tuesday, Saturday-Tuesday [schedule]. We have pretty much the most unprecedented injury situation in that period in the Premier League.
"We played Newcastle before the break, we had no Kepa [Arrizabalaga], no Reece James, no [Ben] Chilwell, no [Marc] Cucurella, no [Wesley] Fofana, no [N'Golo] Kante, no [Raheem] Sterling, no [Ruben] Loftus-Cheek after two minutes and no [Cesar] Azpilicueta. We lost 1-0.
"That was where we were at. World Cup, then the club invest a lot of money in the squad which does that [points up] to the pressure, to the expectation and to the noise.
"The players we have got, they are not 28-year-old, 400 game Premier League players. They are young players who we need to take time to adapt to, but at the same time with the injury situation we had to adapt to try and get them up to speed to do it. That's the position we've been in.
"We thought we were making progress and then we had a first half against Southampton, third game of the week returning from a Champions League game, that was below par. And then the sky can fall in. That's essentially how I could say these are some of the facts. Inconvenient facts if you say 'he's no use' but that's the situation."