Please explain to me how steroids would help you play golf better?
They don't help you play baseball better, either. They do help you keep playing through injuries.
Between added strength and, more importantly, faster recovery from injuries, steroids/PEDs enable humans to play better.
Of all the US-based doctors tiger could have used, he chose a Canadian that had a history in dealing with steroids/PEDs including being busted by Customs.