Just finished watching the video of the Heat game. Incredible. A great offensive game from Reed, and the stat line shows it. Also some nice steals. He's becoming adept at that shoulder turn where he pokes the ball away backhanded. As a stopper, he has his ups and downs. A goat at 5:00 of the 4th, then a stud at 4:00. But the most telling frame is at 3:15. The best spacing I've seen all year. The key is 3 shooters around the arc. Then Sengun has the whole frontcourt to work with. And Amen as a non-shooter can play with that group.
I think having a couple defensive lapses a game can cause people to overstate a player's defensive deficiencies. Luka is a prime example of this - if you look at most metrics, he's actually not a bad defender. However, there are at least a couple times a game that he seemingly gets blown by on defense, and if you string together clips of when this happens, he looks like the worst defender in history. The same is true of Sheppard - yes, there were a couple instances of him getting dominated on defense, but that doesn't mean, overall, he had a bad defensive game. Also, stocks go a long way in making up for defensive limitations. The current steals leader in the NBA is averaging 2 steals a game. In games he's started this season, Sheppard is averaging 2.3 steals.
Some games he plays good defense with a few slip ups. Other games he is targeted relentlessly and plays miserable on that side of the court. The right answer is he is getting progressively better at defense with a lot of the ups and downs of a young player in the NBA. He does have a defensive ceiling of “average” in my opinion, because of his physical limitations. Average will be fine if he is a 40% 3 point shooter.