CHICAGO -- Trading from one area of depth to enhance another, the Cardinals acquired power-hitting outfielder Tyler O'Neill from the Mariners on Friday for left-hander Marco Gonzales.
Cardinals president of baseball operations John Mozeliak described this as a "traditional trade" in that it helped two clubs address needs by swapping controllable young players. Both players were products of the 2013 MLB Draft, with Gonzales taken in the first round and O'Neill plucked by Seattle in the third.
Since then, O'Neill has only augmented his profile. He ranks as the Cardinals' No. 4 prospect, per MLBPipeline.com, and No. 75 overall. O'Neill had 14 homers in his past 19 games at Triple-A Tacoma and was batting .244/.328/.479 with 19 homers, 21 doubles and 56 RBIs in 93 games this season. His 19 home runs ranked eighth in the Pacific Coast League.

O'Neill was the Mariners' Minor League Player of the Year last season when he batted .293 with 24 home runs and 102 RBIs at the Double-A level.
"The one thing that we talk a lot about is finding those bats," Mozeliak said. "This is a player that has a lot of offensive upside. And at 22 [years old], he's accomplished a lot already in Triple-A. So for us, it adds to our offensive depth. [It's] not that we're not proud of our outfield depth, but we do think this offensive profile is unique. [He has] middle-of-the-order potential."
O'Neill will report to Triple-A Memphis, where he'll play alongside another Cardinals outfield prospect, Harrison Bader.
• O'Neill's father was once Canada's top body builder
As for Gonzales, this deal sends him back to a part of the country where he first got on the Cardinals' radar. He starred at Gonzaga University, and he still makes his offseason home in Washington. With thinning rotation depth, the Mariners had been seeking a young starter with multiple years of control as the non-waiver Trade Deadline approached.
Gonzales made a rapid rise through the Cardinals' system, reaching the Majors one year after he was drafted. But arm injuries and the need for Tommy John surgery in 2016 stalled his impact. Gonzales made 12 appearances (seven starts) for St. Louis and went 4-2 with a 5.53 ERA. He also appeared six times in the '14 postseason.
Gonzales' status as an out-of-options player next year left the Cardinals uncertain of how they'd find a fit for him on the Major League roster.
"When you look at our potential rotation for 2018 and then potentially how he would be competing for innings, it seemed like, for Marco, there wasn't going to be any room at the inn for him," Mozeliak said. "And so we just wanted to explore the best deal we could make for him, and we felt this was it."