"Shuts the left side down". That's how PSG got their corner from which they scored their first goal :
The lad simply has a big problem understanding his surroundings as a fullback.
There's absolutely no way any fullback won't anticipate a pass is going to be made to the winger and instead leave him completely open to get the pass and cross.
The real madness is this picture was repeated 2 times in a row for PSG and he didn't anticipate it both times, and the second one ended in the corner they scored.
If he's sitting back, then he's shite at it.