...it's just one component in the game along with other elements like good shooting, quick ball movement, good ballhandling, blocking out/rebounding, having a high IQ, etc.
Fouss has elite length and is built like a DT, his size and strength gives long/lanky defenders trouble, they don't have the center of gravity to be able to hold their ground and it lets him frequently get to whatever spot he wants on the floor. It's kind of become a CB urban myth when people say he struggles against taller guys. Maybe he struggled against 2 big guys his freshman year when he was thrown into a starting role as a true freshman after we lost Baxter and Rich Harward but other than a tough game vs Aimaq and vs Kalkenbrenner what other bigs did he have a hard time against? You would expect a kid right out of high school to struggle against 2 of the better bigs in the country. Looks like he had a tough game vs Tass at SMC that year as well.
Still he was named All Freshman team that year and then followed that up his soph year being named 2nd Team All-WCC. His numerous injuries were the main thing Fouss struggled with last year (and quick defenses that were good at mixing up where their double-teams were coming from), not really any opposing big men in the Big12. The fact that opposing teams were focusing on doubling him as much as they did even when he was injured is a testament to his rep in the paint.