I would agree that Josh is probably in the range of 2-4 in terms of MVP favorite and there are several whom can make that claim being Murray, Lamar, Herbert and probably Henry. I disagree that Murray is better. If you look at their numbers, they are on par with Murray having better completion%, passer rating and a few other categories and Josh having slightly more touchdowns and less interceptions and fumbles. What separates them currently is the win/loss record.
As for Lamar, I don't think he is playing better, I think because his team is winning and Josh just lost, so your viewpoint is slightly skewed IMO.