I haven't honestly seen him blow too many dunks. I remember one from recently but that's it.
I admit calling him a "great" finisher is probably hyperbole
But acting like he's trash at finishing also just as hyperbolic. He's a terrific dunker and can do so in traffic. Given some more time, I think he will be an above average finisher. Might not have many shots in the paint, but the shots he will get should go in at a high clip.
I'm more than willing to keep him just for his D, though. Especially if we get somebody (a PG) like Trae Young, who obviously sucks at D. Maybe he can be hidden on someone while Blake comes in or Blake can at least harass people when trae would get a breather.