...combination of strength/power and length. His lower center of gravity gives him ability to get to the spots he wants for shots and rebounding and his length allows him to get his shot off over taller guys with ease.
He's absolutely built like a 5 and plays with great effect as a 5, he's just shorter than a typical 5. I think fans forget he's been limited by groin and lower leg injuries for most of the past 2 seasons. When healthy opposing taller bigs struggle against him and his length and low center of gravity.
He had a couple of tough games against taller guys as a true freshman when he had to assume the starting job after Harward and Baxter went down with injuries but those struggles were due to his inexperience and needing to adjust on the fly to playing D1 guys and not HS kids In the paint.