I really don't think there is even a noticeable gap in defensive ability between him and Rune, and I don't think its huge between him and carlos either. He is a great defender, and his long limbs and flexibility make for some good court coverage. He mainly isn't as agile at the net or in transition as either, but i think a big thing is he doesn't have the hands of either yet because it is a neglected part of his baseline basher game. He's trying to implement some softer touches, but it's not natural to him. Regardless I think he's still got potential because of his ability to tolerate and give pace on top of being a great returner. His defensive backhands are top notch, and he really gets to a lot of dropshots that his speed doesn't seem to render possible. He doesn't have the soft touch of alcaraz and rune to really play that cat and mouse up there sure, but I think this can be worked on. Did you see Sinner and Rune's match in Monte Carlo. I am not seeing the gaps you are seeing being appreciable except in serve and bravado.