Care to share your reasoning for him being our "5th best" player?
He's got the 5th best advanced analytics after Kyrie, Horford, Tatum, and Rozier (in that order).
The reason for this is because he's defensively elite without being a large burden on offense. He's easily a top 20 defensive player both on paper and visually, boasting a Defensive Box Plus Minus (DBPM) of 3.2. That's better than Kahwi and Draymond Green, to put into perspective.
Now, I'm not saying he's a better defender than those two, because let's be honest, stats don't tell the entire story. But he's at least in the ballpark of two great defenders and consistent NBA all first team players. I'm also not saying that he has more value than Jaylen Brown. I'm simply saying that if you measure our team right now, he is playing better than Brown, Baynes, and anyone else not mentioned earlier.
He's also a rookie. Danny really knocked it out of the park on this guy. I'd wrap him up on a long term contract ASAP. Oh, he's also ranked 84th in VORP... as a rookie... VORP is my favorite algorithm to model player production, because it weighs their contribution against the percentage of minutes played. Even though it's unfair to the player, it gives you a good idea of their exact contribution to the games, because someone playing fantastic for 48 minutes is more impressive than someone playing fantastic for 15. For someone to be ranked 84th in VORP and only play 30% of the game (15 minutes), it's pretty impressive.