Depending on who it draws I've generally been seeing either 2/3 wins or 3/3 wins. Kind of depends on the difference in health (with about 88k health myself, an opponent with only 53k health is probably an easy win while an opponent with anywhere around 80k-90k could be a close match) and depends on who lands some crits (which we're all at the cap of 25% chance).

But yeah, the wins are very hit or miss for whether any mojo is included in the rewards. (Because mojo has nothing to do with level differences or any other stats, only the difference in your current spots in the global tower rankings.)