here is one using my EF50 "nifty fifty" in the same gym during practice. I'm having a hard time with focusing using the back button. Are you suppose to keep it held down when pressing the shutter or let go once focus is achieved.
With this lens I am able to drop down to ISO1600. I've cropped it a bit and sharpened and removed some noise. Maybe I too will go ahead and buy an EF 85 1.8. But I need a 70-200
If you have set to AI Servo, keep it pressed to maintain focus. If on single shot, once it locks on you have to lift off then press in again. When shooting sports you'll want to use the AI-Servo. After a few games (took me almost a full FB season to 'master' it) you'll get proficient with using it. It is not second nature for me to release it when another player runs between me and my subject.