That's fair. I agree the team is to inconsistent. Its common that young players are inconsistent.
The question then is who's fault is it? The manager, the players, or both.
I really like Pep's quote: “My job is taking you to the final 3rd and your job is to finish"
Is it the managers fault Werner misses 19 out of 20 chances in the final third? Johnson and Richarlison are better finishers, but only marginally, and Son isn't the player he was even 12 months ago.
Or that a world cup winning CB plays as if he DNGAF? Or EPL-standard defenders are caught out ball watching?
I just don't think the solution is as simple as sacking the manager.