You have to manufacture a situation that looks bad on slow motion replay.
The refs are grim, VAR has just gave them another chance to prove their incompetence.
That said, obviously the Brentford pen was correct.
That's the thing, it was a pen on Rondon the difference is a player with a bit of snide (Salah) would have made the most of it to make sure he got the pen.
Can't believe there are a few on here who are saying it wasn't a pen for Brentford, it was a clear and obvious pen.