daredevil
Disagree with this assessment, only because I don't think it's an either or situation. There's different phases and aspects to build-up. In a slower build up in a low block, Xhaka' made those same underlapping runs that would give Martinelli space to drive inside. He just did it more intelligently. He knew when to leave him alone, when to support, when to create space. Similarly he got into those same scoring positions without interfering with Gabi. Havertz does the right things but in the wrong way, the wrong time and with the wrong intensity.
Besides, the things that make Havertz's passing game weak also impact his goalscoring role. Havertz's has the lowest number of shots per 90 vs all of our other attacking players, by a fair margin too.
Simply put, the issue isn't with his role or the role envisioned for the left 8 sport, it's with him. The intensity on the ball is the missing ingredient.
