I have no idea why he used them, but he certainly didn't become a s***** player after MLB drug testing began.
This was his reason for using them
"Back then, [baseball] was a different culture," Rodriguez said. "It was very loose. I was young. I was stupid. I was naive. And I wanted to prove to everyone that I was worth being one of the greatest players of all time."
"I did take a banned substance. And for that, I am very sorry and deeply regretful."