His shots to goal ratio last season is not ideal, but it went from 24% to 8%!!! Do you not realise how bad that is? He might've been a chance bottler, but this is a whole new level. 8% shots to goal ratio should be surprising.
There is no other explanation as to why Wernere finishing got worse, but the fact that being a Chelsea player puts a lot of pressure on him. Mental toughness is not just an 'argument', but according to the best football players that have graced this earth it's the most important thing a player can have.
I pray he overcomes this phase in his career and picks up form next season. Things have not been looking good for him though.