Thomas,
You are absolutely correct! In addition to accountability, I would add "consistency" as also crucial to improving team performance. Holding only some people accountable and not others, or not holding people accountable on a consistent basis, will result in performance suffering.
I also agree with your former supervisor. I'll take an employee with passion about what he or she does any day over somebody with just knowledge and no commitment.
Nicely stated.
Thanks,
Jamie