well in the current subject of the York Arms: it's not so much a case of them not lasting long as they appear to have been a temporary measure to keep the pub open... they were offered a pub in London (can't remember it's name) before they had been in the York Arms for 2 weeks... that was the area of the country they wanted to be in so they took it.
and as is the case with sam smiths, everything happens fast, they were offered the position one day and were gone from the pub the next.
this may or may not be helpful but is my understanding of the recent changeover... somebody else may have more info.