SEATTLE -- Jerry Dipoto said Thursday he would only give up one of his elite prospects if he could land a starting pitcher who would be under team control for multiple years, and the ultra-active Mariners general manager pulled that off Friday, dealing highly regarded outfield prospect Tyler O'Neill to the Cardinals for 25-year-old left-hander Marco Gonzales.
"Marco is a quality athlete with high character and a strong pitching pedigree who we feel fits our roster well in both the near and long term," said Dipoto. "We find his current performance, preparedness and proximity to the Major Leagues to be very appealing traits in a pitcher, particularly a young lefty who is now under club control through the 2023 season."
Gonzales is a former Gonzaga University standout who was on the fast track to the Majors after getting drafted in the first round in 2013 until being sidelined by Tommy John surgery last year. He has spent parts of three seasons in limited time with the Cardinals and was 6-4 with a 2.90 ERA in 11 starts for Triple-A Memphis this season.
Gonzales, who will report initially to Triple-A Tacoma, was the No. 18 prospect in the Cardinals' system per MLBPipeline.com, and he has initially been ranked as Seattle's No. 7 prospect. He has gone 4-2 with a 5.53 ERA in 12 Major League games (seven starts), and he also posted a 4.50 ERA in six innings of relief in six games in the 2014 postseason.

O'Neill was Seattle's No. 2-rated prospect, per MLBPipeline.com. He opened the season as the 36th overall prospect and was ranked No. 29 at the time of the trade. The power-hitting outfielder from Canada, who has initially been ranked the Cardinals' No. 4 prospect, hit .326 with 13 homers and 31 RBIs in his final 24 games at Tacoma.
With Drew Smyly out for another year following Tommy John surgery and Hisashi Iwakuma's future in doubt due to lingering shoulder issues, Dipoto has been looking for starting-pitching help -- both for this year and beyond. In Gonzales, he landed a young starter with promising upside and six years of team control.
Since June 18, Gonzales is 5-1 with a 2.61 ERA in six starts for Memphis. He made one Major League start this year, pitching the second game of a doubleheader on June 13 against the Brewers, allowing six hits and five earned runs in 3 1/3 innings.
The 6-foot-1, 195-pound lefty has twice been listed by Baseball America as having the "best changeup" in the Cardinals' organization (2013-14) and he was the Cards' Minor League Pitcher of the Year in '14 before missing part of the '15 season with a left pectoral injury and all of '16 following Tommy John surgery.
Gonzales lives in Seattle in the offseason, and he was the highest Draft pick in the history of Gonzaga's baseball program when he was taken with the 19th overall selection in 2013.
The price for acquiring Gonzales was high, as Seattle gave up one of its top position prospects in O'Neill, a 22-year-old Canadian who was hitting .244/.328/.479 with 19 home runs and 56 RBIs in 93 games for Tacoma.
O'Neill was a third-round Draft pick of the Mariners in 2013, and he played three games for Canada in the World Baseball Classic this spring. O'Neill was the Mariners' Minor League Player of the Year last season, when he batted .293 with 24 home runs and 102 RBIs for Double-A Jackson.
"This was more of a traditional trade in the sense that O'Neill was an outfielder with upside in the Mariners' organization and Gonzales was a pitcher with upside in our organization," said Cardinals president of baseball operations John Mozeliak. "If you look at the depth we have with the pitching in our system, it allowed us to make a move like this to improve."