The Cardinals have traded David Freese (and reliever Fernando Salas, who they probably would have non-tendered) to the Angels for Peter Bourjos and outfield prospect Randal Grichuk.
The Cardinals' defense was the one element of their team that was questionable last year, particularly in the outfield, and this really helps them. Bourjos is a tremendous defensive center fielder, and he's not a total zero with the bat. It remains to be seen how the Cardinals will use him, but you can expect to see a lot less of Jon Jay in center field. Freese had worn out his welcome in St. Louis, and they're unlikely to miss him, with Kolten Wong taking over at second and Matt Carpenter heading to third. Freese's defense took a nosedive last year, too, so Wong/Carpenter is probably a defensive upgrade in the infield as well.
In other words, the Cardinals didn't give up anyone who figured to play a big role on next year's team, and they upgraded their defense significantly. Too bad for us.