49ers - He gained 150+ yards against. Not sure why he would not do good against good defenses. Also faced Texans (Probably around 10th ranked defense or so and gained 170+ yards. Seems do be doing okay against them.
And if you want to state about playing against good defenses, look at the Seahawks schedule as well. Bengals, Steelers, Bucs, Browns, Falcons, Cardinals...Compared to Panthers who have played the Bucs (2x), Cardinals, and other mediocre teams. Both teams have not had too many big games as of yet against good defenses. I admire the 22 TD to 1 INT because he does not give the ball away. Strength of schedule had Seahawks having a much easier schedule (I think). So I think the argument of going against better defense is null and void between the two.
For your question of if he does not make 300 yards a game, he should not be MVP. The answer is hell no because he definitely will not be the best at his position. If Seahawks lost Wilson, they still have Carson at RB and all their WRs (maybe the best core in the game with Metcalf) and could probably win some games. If Panthers lose McCaffrey, who does the work? Their QB, RB, and WRs are not that great and he carries the team every week. Everyone knows he is going to get the ball and still does not get stopped. I think it will be a close race down to the end between a couple of people though. Will be interested to watch!