I think he's the scariest opponent in the league now, so everyone should be concerned. Im more worried about them than Toronto. Leonard is playing at an all-NBA level and has the experience, but Giannis has more peak potential than even LeBron did. It is physical impossible to stay with his pivots, even when they are air tight and legal.
What impresses me the most is his natural sense of aggression and competitiveness. I think it separates him from Anthony Davis, who is as big and almost as athletic, but with more complete basketball skills. Giannis wants it, and it will not be easy to stop him from getting it.
I do think we are the best matchup against him, and Jaylen is crucial to that. Brown covers more perimeter space around the three point line than any defender in the league. When he's out, we just don't contest the same way. He's also the only guy we have that can compete athletically against him. The only way to slow Giannis down is to close up as much space as possible, and that takes lots of length.
We'll see how it goes. Right now, Giannis is right there at the top with a handful of other MVP candidates, but he's the one with the most potential to separate himself from the pack. History shows that when one guy is clearly better than everyone else, his team has a 50/50 chance or better of winning a title.