Starting pitcher Steven Matz, a key component to a turnaround season for the Toronto Blue Jays in 2021, has agreed to a four-year, $44 million deal with the St. Louis Cardinals, pending a physical, sources familiar with the deal told ESPN's Jeff Passan on Tuesday night.

Matz could earn up to $48 million in the deal and will receive a signing bonus, sources said.

Matz, a 6-foot-2 left-hander, who found his stride in the American League East and on a team with a deep starting rotation, often stole the headlines in Toronto last summer. In just one season with the Blue Jays, he posted a 14-7 record, with a 3.82 ERA in 29 starts.

He finished with 150⅔ innings of work and 144 strikeouts as Toronto threatened for a playoff berth well into the regular season's final week. The Blue Jays won six of his final seven starts, and in his last one on Oct. 1, Matz -- tabbed one of the team's "unsung heroes" by manager Charlie Montoyo -- pitched seven innings en route to a win over the Baltimore Orioles. Toronto finished 91-71.

"Looking at this team, I'm like, 'Man, this team is so good. We're so close,'" Matz told reporters in the final week of the season in Toronto. "I don't know if I've ever been on a team this good."

Matz, 30, a second-round pick of the Mets in 2009, was one of many pitching prospects New York hoped to build title teams around, along with Noah Syndergaard, Jacob deGrom, Matt Harvey and Zack Wheeler. A New York native, Matz seemed destined for success with the Mets, especially after going 4-0 as a rookie in 2015, the same season New York landed in the World Series against the Kansas City Royals.

A string of injury-filled and inconsistent years followed that magical season in Queens, and Matz ended up in a deal with Toronto on Jan. 27. In 2020, his last season with the Mets, Matz finished 0-5 with a 9.68 ERA as he battled shoulder discomfort, eventually being relegated to the bullpen. His two best seasons in New York -- apart from his debut campaign -- came in 2016 and 2019, when he combined to go 20-18.

But it wasn't enough to keep him in Queens, as the Mets shipped away the veteran -- and his $5.2 million salary -- in exchange for some minor-league pitching depth before spring training. The Mets received right-handers Sean Reid-Foley, Josh Winckowski and Yennsy Diaz. Matz received a second chance.

"He's been one of the unsung heroes here," Montoyo said in the season's final week. "Nobody expected him to pitch like that. Almost every time out, he goes five, six innings and keeps us in the game. He's been really good. Great, actually. Not good, great."