Chelsea was a disaster, but he was dealing with a whole new team that had never played together.
That part definitely wasn't true when he first took over though. Things changed drastically in the January window when we had new players coming in the door every few days but the first few months into Potter's time at Chelsea the team was still largely the same as the previous couple seasons under Tuchel.
Potter's first game in charge included Kepa, Silva, Chilwell, James, Jorginho, Kovacic, Mount and Havertz in the starting lineup. The likes of Pulisic, Loftus-Cheek, Azpilicueta and Chalobah also saw plenty of playing time early on and they'd been with the squad a long time by then. During the first half of 22/23 the only new players who saw any significant minutes were basically just Sterling, Koulibaly and Cucurella. Fofana got injured early and Aubameyang hardly ever played.
By the January window the season already looked like a write-off so the club decided to jump-start the coming squad rebuild earlier than initially intended, which made the squad very bloated and definitely made Potter's job a bit harder in the short term but it's not like things were going even remotely well before that either.
Either way, despite his struggles with us I still think he's a very decent manager but just wasn't the right job for him. Looking back now the red flags were there from day one and it's almost like he couldn't believe his luck in landing a job as big as the Chelsea manager. Mentally he didn't seem ready for such a big task and I'm sure the players could sense it too, which may have been why they never fully bought into Potter's ideas because they just didn't respect him enough, the cnuts. So yeah, the club leadership and the players definitely made his job harder than necessary but Potter still deserves a lot of the blame for his failures with us.
That being said, I really don't see how he does any better at United than he did with us. The job over there seems just as hard, if not harder, as the Chelsea job and he's already shown crumbling under the pressure once. I think he'd be better off taking on an 'easier' project somewhere a bit smaller, like say Palace, West Ham or wherever a suitable job opens up next. A couple years getting his career back on track before trying to land another top job again could do him a lot of good. Then again there's always the possibility that failing at wherever he'd end up next would close the doors of the top clubs to him forever so he might be very tempted to accept the United job if it were offered to him.