As others have said, he played superbly at right back last season.
Playing on his weak side vs one of the best players in the world was always going to be a challenge today. No need to overreact.
All the reporting has been that PSV don't want to sell and it would take a crazy offer, but there has been no suggestion as to what that would be.
Sounds like we bid around €10m.
I know the SPL is shit but I don't think Celtic would be interested in a soon to be 22 year old with less than 10 senior appearances (most of which were in L1).