The Jedd Gyorko/Jon Jay swap looks a bit like a salary dump, and perhaps a trade of two disappointing players, but it allows each club to achieve something important: cost savings for the San Diego Padres, and moving a surplus player to fill a critical bench spot for the St. Louis Cardinals.
The Padres' main get in this trade is the salary commitment they're subtracting; Gyorko's contract extension, handed out by the previous regime in April 2014, has been an unmitigated disaster for the team, as he has hit .233/.292/.369 in 853 plate appearances since signing the deal. San Diego will save $18.5 million in this trade while opening up second base for some combination of Cory Spangenberg, Jose Pirela and newly acquired Carlos Asuaje. They do still need a shortstop solution, but at least now they have some free cash to take on a higher salary at that spot.
If Jay's wrist checks out and he's able to swing the bat in 2016 like he did before the injury, the Padres just picked up one year of a solid 2-2.5 win outfielder who can play center field, perhaps platooning with Melvin Upton Jr. there or handling the bulk of the duties in left field if San Diego doesn't acquire a full-timer for that spot. I don't think outfield prospect Hunter Renfroe will be ready to handle regular duties in the majors until later in 2016 given his difficulty getting on base since he left Class A ball, but the Padres could choose to leave an outfield spot open or flexible for his eventual arrival.
The ideal outcome for them this winter would be to acquire one more major league-caliber outfielder as well as a true shortstop, and if they want to rotate a few kids through second base to keep the cost down at that position, they won't be any worse off than they were with Gyorko there every day.
The Cardinals, meanwhile, take on some salary commitment to acquire a super-sub who has badly underperformed since that contract extension, but whose minor league performances pointed to better major league production, especially power. Gyorko can handle second or third base -- not well, but adequately -- and is an emergency shortstop who might allow the Cardinals to dispense with a Pete Kozma type on the bench, someone who occupies a valuable roster spot solely for his ability to play short. As bad as Gyorko's overall stat lines looked the past two years, he has posted a .351 OBP against lefties over those two seasons, which particularly helps the Cardinals thanks to their left-handed bats at third base (Matt Carpenter) and second (Kolten Wong). Wong has hit .248/.282/.325 against lefties in his big league career, and his OBP would be just .265 if it weren't for the six times he has been hit by pitches from southpaws, so platooning him with Gyorko, while less than ideal for Wong's development, makes the team better right away.
Jay had no place left to play in St. Louis with the emergence of Stephen Piscotty, Randal Grichuk and Tommy Pham as major league assets, and that's assuming they don't re-sign Jason Heyward or acquire another outfielder. Given the way the Cardinals are likely to use Gyorko, they should get their roughly $4.5 million per year's worth of value from him.