This is a fun convo since everyone seems to have a different definition of what the MVP is.
It's hard to just say "if you took him off the team their record would be........". That just means he is the MVP of his team, not necessarily the league.
If you took Rivers of San Diego, they might win 1-2 games, but that doesnt make him the league MVP.
A guy has to obviously be playing great, leading his team, winning games, and be the best at his position (or at least top 2). Stats are part of it, wins are part of it, the team around him is part of it (although highly subjective), and what would happen to the team if that player got hurt is part of it (PART, and HIGHLY subjective).
And in the game today, I can not imagine this player being a defensive player, even a guy as great as Watt. I really cant imagine it being anything other than a QB right now. I suppose things can change, but if you try and tell me someone is more valuable to their team in in the league than Manning, Brady, Luck, or Rodgers (and I can even add a handful or more guys to this) then I will tell you that you are insane.