Before anyone jumps the gun on the swelling either, that's normal for pretty much any kind of damage to a joint, be it connective tissue, soft tissue, or bone matrix.
What makes the swelling a positive is that it's a great way for the body to make sure that the joint isn't taken to a point where more damage can occur. What makes it a negative here is that the presence of the fluid makes a good diagnosis nearly impossible.
If what I'd read already is true (that it involves the articulation of the fibula), the main advantage is that that particular section doesn't bear anywhere near as much weight or pressure as the articulation of the tibia. It would be painful to play on if it's injured. The drawback is that most ankle injuries, particularly in basketball, occur when a player lands on another's foot and the ankle inverts (where the sole of the foot is point in and up rather than down and away). This would make the chance of reinjury much more likely.