The biggest thing that Jokic improved since I saw him as a rookie is athleticism. He always had a acceleration/decceleration ability. Bro used to be so slow and other bigs who were really fast for their size would just get up and down the court much faster and would run him off the floor.
He really worked on his foot speed and even his explosiveness a ton. Sure, he will never be someone who can jump but can get off the court and knows when to do it. Before the used to know when to do it but he was too fat to do it. He's not fast now but he can play at a nice pace, especially in Denver where he is flat out lethal and wears a defense down. I remember playing him last year and being like, oh oh. This nikka is different different. It reminded me of Steph in Mark Jackson's last year.
Everyone remembers 15 and 16. But 14 was when if your team played Steph, you were like oh my. I think 15 is when the rest of the team was finally ready to join Steph.