With cash likely being involved in this deal, it must be approved by the commissioner's office, and that would explain why there hasn't been confirmation on what the Cardinals are getting in return.
The versatile infielder hit 30 homers in his first season with the Cardinals and 50 over his first two, but he's had his role on the team nudged to the peripheral of the roster with the emergence of Yairo Munoz and Tommy Edman this season. Gyorko is in the final guaranteed year of an extension he signed with San Diego for a trade, after the 2015 season, to the Cardinals.