The 85 1.2 is probably the slowes autofocusing L series lens I own.
Too slow for action, this is a portrait lens.

Indoor sports can be a challange.

You might also try the 85 1.8 very fast
135 2.0 very fast

I would use one of these and push the ISO higher (especially on the 5d III) I think you will get more keeps.
THe gold standard is the 70-200 2.8 if 2.8 is fast enough.