Bastardo, 28, served a 50-game suspension at the end of last season for his connections to the Biogenesis scandal. He spent the final two months of the season at home in the Dominican Republic before pitching well there in winter ball. Bastardo is expected to be a key piece in the Phillies' bullpen in 2014.
Asked if he knew what he took was a banned substance, Bastardo said, "Yeah, I know it was a mistake. I told you before it was a mistake that I made. I know what I did."
There was backlash. Former relief pitcher Dan Meyer and Bastardo participated in Phils camp in 2011. Meyer said on Twitter, "Remember when we competed for a job in 2011. Thx a lot."
"I don't know why some players are thinking about that," Bastardo said. "It's like, why do they compete with me? You have to compete with the hitters. You have to get the hitters out. If you do your job, you make the guys who are making decisions think about you. That's it. You're not competing with other pitchers. You're competing with hitters."
Bastardo went 3-2 with a 2.32 ERA in 48 appearances last season. There will be skeptics following his performance this season, watching closely to see if he can pitch successfully after being caught and suspended.
"No, I don't feel like I have to prove myself," Bastardo said. "I feel confidence in myself and what I need to do. Just do it. Just get people out."
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.