The 1-for-1 swap is an unconventional one for this time of year, when teams usually trade veterans for packages of minor-league pieces. In this case, O’Neill has not yet appeared in the majors while Gonzales only has 40.2 innings of big-league time under his belt.
Gonzales, 25, was St. Louis’ 1st-round pick (19th overall) out of Gonzaga in 2013. One of the top 50 prospects in baseball in 2015, the southpaw has worked to a 5.53 ERA and 7.5 K/9 in 12 appearances (7 starts) in the majors in 2014, 2015 and 2017.
Gonzales missed much of 2015 with shoulder issues and the entire 2016 season due to Tommy John surgery but has rebounded to post a 6-4 record and 2.90 ERA over 12 starts with Triple-A Memphis this year. He won’t be eligible for free agency until after 2023 season, giving Seattle more than six years of control.
Gonzales was ranked by Baseball America as the Cardinals’ 13th-best prospect heading into the season and is now ranked as the 7th-best prospect in Seattle’s system, according to MLB Pipeline. Seattle was known to be searching for controllable starting pitching in advance of the deadline and achieved that goal with the outside-the-box addition of Gonzales.
O’Neill, 22, was Seattle’s third-round pick in 2013 and was ranked Friday by BA as the third-best prospect in a weak Seattle system. The outfielder, who entered the season as the 38th-overall prospect in baseball, has hit .244/.328/.479 with 19 homers and 56 RBI in 93 games for Triple-A Tacoma this season and is regarded as one of the top power-potential bats currently in the minors.
He was immediately ranked by MLB.com as the 4th-best prospect in the Cardinals’ system, ranking only behind Alex Reyes, new call-up Carson Kelly, and Luke Weaver. A year after posting great numbers in Double-A, O’Neill has regressed a bit at Triple-A, falling out of the top 100 prospects in baseball. He joins Dexter Fowler, Tommy Pham, Randal Grichuk, Stephen Piscotty, Magneuris Sierra and Harrison Bader in a crowded Cardinals outfield mix going forward, giving the clubs some potential trade chips.