Heres something I just though, correct me if I'm wrong (don't know if it relates to Mir).
TRT helps older fighters recover quicker from training and helps them keep in good shape.
Older fighters are more prone to serious injuries.
Does TRT actually help them PREVENT injury, or just help with recovery time? Because if so then the older fighters getting injuries might just be a sign that they are too old to compete, and the only reason they can train and fight is the TRT. This could be pretty much the first and so far only downside to TRT...