ST. LOUIS -- The Cardinals filled the biggest void in their bullpen Monday with Brett Cecil, the only left-handed reliever that piqued their interest on the free-agent market.

Cecil was introduced at Busch Stadium after finalizing a $30.5 million, four-year contract. He is expected to provide help in high-leverage situations along with Kevin Siegriest and ahead of closer Seung Hwan Oh, though general manager John Mozeliak said all three are capable of finishing games.

"Brett was the one person we thought if we were going to make a splash in the bullpen, he was the one we identified," Mozeliak said. "There was a lot of demand for him and it was moving."

The four-year deal for the 30-year-old Cecil gained attention, but Mozeliak said he was comfortable with the length of the contract because of the interest he was generating.

"Our offseason plan has been to take steps to try to improve this club and certainly today we feel like we have," Mozeliak said. "I think it's a way we envision keeping a fresh bullpen."

Shoring up the bullpen became one of the Cardinals' biggest needs following injuries to Zach Duke and Tyler Lyons. Duke is expected to miss all of next season after Tommy John surgery, while Lyons has had offseason knee surgery that leaves him questionable for the start of the regular season.

Cecil had a 3.93 ERA in 36 2/3 innings for the Blue Jays last season. He was slowed by a torn lat muscle but dominated down the stretch, tossing 3 2/3 scoreless innings in the playoffs.

"The lat issue, it was kind of an accumulating thing," Cecil said. "We tried to rest, tried to let it heal. It wasn't working. I was sidelined for six weeks. I almost had to start spring training over again in the middle of the season. It took me a little bit to get going, and there in August and toward the end of the season and in the playoffs, I was beginning to feel like my old self again."

Cecil, who had a 2.90 ERA in four years as a full-time reliever in Toronto, was testing free agency for the first time. He said that he left most of the negotiations up to his agent, but he was happy that a deal got done relatively early in the process.

"I honestly didn't know when it was going to happen," he said. "I do like to get these types of things over and done with as quickly as possible. That way I can get my focus more toward the offseason, to come to spring training ready to go."

Under the deal negotiated by agents Sam and Seth Levinson, Cecil gets a $1 million signing bonus, payable within 30 days of the deal's approval by Major League Baseball, and salaries of $7.5 million in each of the next three seasons and $7 million in 2020. He also receives a full no-trade provision and award bonuses.

Cecil said he doesn't know anybody on the current roster, which is still in need of an outfielder, but that the longtime American League pitcher is ready to take on the National League.

"Absolutely. This team is rich with baseball history," he said. "They have a rich winning tradition. They always have good teams -- good, winning teams. And like I said, for my family and me, this is where we wanted to come. It was the best fit for us."