He was the signing of the season for us, but has clearly had difficulty adjusting at Chelsea. I would still back him to come good though, just as I would with Potter as well. He had an awful game last night, but there is an excellent player in there.
He played behind March quite a bit last season who is good at tracking back and the CBs he played with, generally Webster and Dunk are very mobile as well, maybe more so than Thiago Silva and Koulibaly so it was rare he was ever isolated. I remember White being written off at Arsenal in his first season there and he struggled under his price tag as well, but he is generally loved at Arsenal now, I can would predict a similar journey for Cucurella.
Chelsea are a funny and unsettled team at the moment, whereas Brighton were and still are a settled happy, very well drilled group and until Potter achieves that at Chelsea, then I think players will struggle a bit. But clearly Cucu had a stinker against City!