I've been saying it for months that it should be between him and Harden, but for whatever reasons he is getting ignored in the discussion.
He is the best performing player in the league. Likely the best defender in the league, in addition to being a top 5 attacking player. If Spurs get the best record in the league, then it shouldn't be even a discussion about who should get the award. Really, without him Spurs are nothing. In each critical moment, he is stepping up, leading the team to victories and getting the responsibility for the final shots.
I think that today it was my favorite Kawhi moment. Scoring a triple in the last seconds of the match (in an another 30+ match) and then making a run to make a brutal block on James Harden to keep the advantage. Then being chased by the entire Rockets team and still managing to not get fouled and so getting an important victory.
While it should be between him and Harden, I had the opinion that Harden should be the favorite (because of amazing stats), but really I am starting to change my opinion. On attack, Harden is still better, but if you are in the closing moments of the match, and you can choose one player for the action in entire NBA, I would choose Leonard. And considering that the defense is as important as attack, Leonard being the best defensive player in the league with Harden being one of the worst, that is a real advantage for Leonard.
Leonard would be the MVP if only the decision makers can look past the stats. He is essentially playing like James at his best.