One of Lewis' strengths has always been his ability to get involved in the car design without upsetting the process too much - most drivers just let it happen, but Lewis (like Schumacher did) always wants to know what's going on in the factory... this season with a car he had no input into that clearly wasn't contending, honestly I think he ended up checking out... once he realised the car was going to struggle he only gave 75% - there's no way Leclerc should be outperforming him this regularly.
Next season with the new car is the real test for me. If he's still not competitive, it might be time.