Irreparable harm is pretty easy here. Yes, courts usually consider monetary reimbursement as repairing harm, but not in the case with professional athletes. It's common knowledge that an athlete's career is typically very short, so not allowing one to participate during this short period is harm that can't be repaired by money. This isn't an accoutant with a 40 year career.
The good news is you and I don't get to decide. The judge decides which one of us is correct. Hopefully in less than 15 minutes.