From start to finish Mackinnon was the best player in the league last season, you can disagree with that if you want but Colorado had horrendous goaltending, injuries, horrible depth at forward, Nishuskin missing close to 30 games and Mackinnon kept that team going all season.
Tampa Bay had three 40 goals scorers, six 20+ goal scorers, five 70+ point scorers and even with Vasilevskiy having a bit of a down year, that is still far better then the awful goaltending Colorado had last season. So I think Mackinnon was the very well deserved winner last season. People can disagree on that but Kucherov definitely doesn't deserve it this season.