This is a fun prompt, the SHL is actually a testing ground for lifelike robot's to be stress tested. Think the institute in fall out, each team is controlled by a scientist that is making these robot's so each team is slightly different. When the robot is deemed to be too damaged (injured) to continue it is destroyed (retired) and a new robot is called up from the Juniors.

The Junior League is run by low level scientists whose creations are drafted by the senior scientists who they report to.

The robot's have some level of machine learning, this is why they tend to get better and better until the damage catches up to them which makes them less and less effective. Don't ask me about contracts and the salary cap because I haven't figured out a way to include them in this little SHL world that I have created.