General manager John Mozeliak said Monday that Peralta had admitted wrongdoing and served his penalty and that the Cardinals weren't about to appoint themselves morality "police." Mozeliak said the club was confident that this was an isolated circumstance.
"Character and makeup are something we weigh into our decision-making," Mozeliak said. "In his case, he admitted what he did, he took responsibility for it.
"I feel like he has paid for his mistakes, and obviously if he were to make another one, then it would be a huge disappointment."
The 31-year-old Peralta was suspended for 50 games last summer following Major League Baseball's investigation of the Biogenesis of America anti-aging clinic, which was accused of distributing banned performance-enhancing drugs to players.
Mozeliak agreed with critics that penalties aren't strict enough.
"You do need a deterrent, and right now 50 games does not seem to be necessarily stopping it," Mozeliak said.
But he also believed attitudes have changed.
"I think Major League Baseball has done a great job trying to clean up this game, and I feel like they've taken great steps," he said.
Mozeliak said in a statement Sunday that the Cardinals were "pleased" to sign Peralta, but the move drew a different reaction from some big leaguers.
Although he did not specifically name Peralta, Ziegler expressed his opinions in a series of tweets.
People really don't understand how this works. We thought 50 games would be a deterrent. Obviously it's not. So we are working on it again.— Brad Ziegler (@BradZiegler) November 24, 2013
Just trying to make our game better when I leave it than it was when I got into it. Don't have all the answers, but trying, & MLBPA knows...— Brad Ziegler (@BradZiegler) November 24, 2013
Free-agent pitcher David Aardsma also took to Twitter:
Apparently getting suspended for PED's means you get a raise. What's stopping anyone from doing it? #weneedtomakeachange— David Aardsma (@TheDA53) November 24, 2013
I had 2 major surgeries in 5 months and made it back clean, nothing pisses me off more than guys that cheat and get raises for doing so— David Aardsma (@TheDA53) November 24, 2013
Peralta underwent a physical Sunday, though he did not attend the introductory news conference.
St. Louis also explored a trade but wasn't willing to part with several prospects. Mozeliak said negotiations went quickly after groundwork was laid at the GM meetings.
Peralta and Stephen Drew were the top two shortstops in free agency. Peralta was a plus for the Cardinals because they've got a lot of left-handed hitters and he bats right-handed.