One of the first defensive lessons in basketball is "See your man, see the ball."
Notice how Reuben slides from post to corner and back with a textbook lateral slide, the defensive posture drill teams do over and over but one which most kids abandon during play because it's tedious.
I'm prepared for him to go back to Spain next season since he is on loan for just one year. Not sure how NBA notice would give him reason to stay, or even if that happens, may be beyond his decision.
For now just enjoying the heck out of one of the most fundamentally sound freshmen we've ever had. His play here can only result in more interest from abroad.