That's what worries me. Were it not for the offside, this would have been a penalty.
It isn’t the kind of defensive stance you expect from a defender, but you can't put all the blame on him because he's only been converted to this position recently. Any smart team will spot that and exploit it. Imagine him got dominated by cunning wingers like Orsoloni, Neres etc.
So like other members have posted, this LCB experiment might work long term for Koop, or it might not, esp if Spalletti switches to a back four.