Heck yes--all three years. The first year I watched him we were still playing in the Smith Field House.
As I recall, and I am not looking this up, our other starters were Bernie Fryer, Steve Kelly, Jim Miller and Phil Tollstrup. I was only 12 years old. I freaking loved Cosic and the rest of the guys as a kid. I thought they walked on water. My parents would drive me down to Provo from SLC for the games. The game atmosphere was electric. And we were so cool with our shaggy, lanky, unstoppable, communist defector center. Here's the tune the BYU band played back in the day during time-outs. It takes me right back through 48 years to the field house and the first couple of years in the Marriott Center with Cosic. I get emotional just thinking about that team and head coach, Stan Watts. https://www.youtube.com/watch?v=TXvegzWNIps