It always helps a LOT when you explain what you're trying to do as it changes the whole picture drastically.
In this application, the speed of the ball will be quite slow. It's moving along a rail, so fixed path, and maybe fixed orientation even (can't rotate around the rail). In that case you can attach a magnet to the ball and use reed switches or hall effect sensors to detect it's passing.
These switches (or break beam sensors) will be wired to your Arduino (why not directly to your Yun?). Just one can handle all sensors just fine. Add one at the very bottom - that tells you that a hit has been made (the ball is gone), and when the hit is finished (ball fallen back down). When finished, it can send out the data to a server or whatever you want it to go to.
I don't see the need of a wireless link between the high striker and the yun, only to have the yun send the data onwards, as you'll need another microprocessor to take the readings from the sensors.