Hard to fully evaluate his defense because Boyle played so much zone, at least in the 3 full games I watched in the Dick's National Championship series. He played the 5 and the 4 at different times.
Offensively, Montverde didn't use their bigs as post options because they have 2 amazing 5-star slashers who they want to keep the lanes open for. Most of Sandro's points come on drive and kicks to him near the basket (where he is an excellent finisher) and offensive rebounds. He also spends time on the perimeter setting screens ( very good screener for HS kid), making good passes and popping open for 3s.
He mostly played the middle '5 spot' of the 2-3 zone. He moves pretty well laterally and challenges shots. I think he is a solid rebounder and active defender with ability to greatly improve at both.
He will get regular minutes as a Freshman because of his offense but I also think he can hold his own as a defender and rebounder. His combination of length and agility alone will help though he will struggle with the more physical inside players as most freshman do. His ability at 6'10 230 is the best we've ever had, up to him and the staff to develop it and use it properly. If Duval comes I think he would get him a lot of points on drive and dishes and alley-oops and think they would form a great pick and roll, pick and pop duo.