I get your frustrations. They are pretty common for wrestlers coming into jiu jitsu. From what you describe in sparring, I think a comparison to wrestling might make sense. Imagine if a really big and strong jiu jitsu player came to a wrestling practice. During live goes on the feet, he avoids ties, circles away, and doesn't take any shots. On the mat, he clams up on bottom and doesn't try to escape. On top, he will throw legs in and can ride you out, but doesn't try to turn.
That's basically what rolling with a raw or relatively new wrestler in BJJ feels like. Wrestlers hate stalling and so do jiu jitsu players, stalling just looks a bit different in each sport. I think coaches in either sport would rather see someone in practice get pinned/submitted/scored on trying to score themselves rather than stalling.
So, don't worry about getting swept or tapped. Try to pass, play bottom, pull guard yourself. I think that will make the sport a lot more enjoyable for you and your partners.