It's used in rugby too, but it's only player tracking involved. That's a much simpler problem and, as mentioned in the paper, is fairly easily solved.

I think the USP here is being able to measure the path, velocity and spin of an object in flight, and how this is much more easily done using instrumented equipment, rather than ultra-expensive cameras.

I can imagine this solution could also be applied to many other ball sports, eg baseball (as mentioned), golf, tennis, etc. Maybe also for T&F throwing events.

In my own sport, rowing, equipment to measure stroke angles and force curves is become ever more readily available and cheap (important in a sport with not much money flowing around). Low-cost ubiquitous IoT in sport is definitely a growth market.