He peaked in the period beginning with his final season at Celtic, his Southampton spell - and he carried that form over to the half season he had when joining Liverpool from January-May 2018. He was an all action up and down the pitch CB and did it very well indeed.
Since then he predominantly plays at the back as some glorified sweeper and it neutered him. Now even that limited role is a busted flush with the injury he got last season.
He's finished. Completely finished. No way would City or Chelsea or even United look at him and want him now.
He'll be playing for Ajax in a season or so, then Go Ahead Eagles to end his career.