Jaren Jackson, Jr. is a promising young player, but his defense has a ways to go. His defensive impact stats are middling or poor by the advanced metrics, so I dug into the tape to find why. A couple examples: The Nikolas (Vucevic and Jokic) shot 12/18 (67%) against JJJ. Thread:

Needs to move feet quicker against skilled bigs. Vucevic here blows by JJJ on the drive.

2. A similar play earlier in the game. Playing far too close up on Vucevic at the elbow, letting him go left for the drive and score.

3. Jokic here. He's a load but JJJ too easily gets bodied. Needs to push back a bit more here.

4. Too slow to react to the Jokic spin. Joker is quick and able to take advantage with the reverse.

5. Again, JJJ needs more strength here. Allows Jokic to get position and bully in for the layup.

6. More of an effort play here. Late contest on the three and then slowly comes back into frame while Jokic gets the tip-in.

7. Overcommits after the hand off, leaving no one to guard Jokic.

8. JJJ again overcommits and leaves Jokic open. Shows the genius of Jokic though to immediately go up with the shot after the bounce pass.