So long as Ryan Jackson is active in place of an injured David Freese, the St. Louis Cardinals will have three shortstops on the 25-man roster. Daniel Descalso should take this opportunity to breathe deeply and relax a little: When Freese comes back, and Descalso returns to the bench, he will officially be Everybody's Backup. That's thanks to the Cardinals' strange bench construction: Matt Adams and Ty Wigginton will make up an Earl-Weaver-style platoon of backup first basemen and pinch hitters, leaving Descalso as the sole backup middle infielder and Shane Robinson alone in the outfield.
What makes that possible is the versatility the Cardinals have in their lineup. Matt Carpenter is the starting second baseman, the backup third baseman, and an almost-convincing outfielder; Allen Craig is the starting first baseman and the fourth outfielder. So it doesn't matter that Matt Adams can only play first base, and Ty Wigginton shouldn't play anywhere at all.
At shortstop, though, Daniel Descalo's it, just a year after the Cardinals seemed unconvinced about his defense at the position. He's also Matt Carpenter's defensive caddy. He won't be starting at second base once Freese comes back, but I'm not sure he'll be any less busy.