General manager John Mozeliak referred to the move as mostly precautionary, and said that it's possible that Sanchez will miss only the minimum 15 days. Sanchez, who typically pitches at 94-95 miles per hour, didn't crack 90 mph in his last outing, on Sunday in Milwaukee. That raised concerns for the Cardinals, and on Thursday the rookie was checked out by the club's medical staff. The DL stint was made retroactive to Monday, the day after Sanchez last pitched.
Sanchez tweeted Thursday, "Nothing bad with [my] shoulder will be back soon..."
Mozeliak, however, said, "The key thing is, once he gets back his flexibility and strength, then it becomes just getting him back into that throwing environment. Could it be as short as the back-date, two weeks? Yes. But it could take a few extra days just to make sure."
Pitching coach Dave Duncan expressed a desire on Wednesday for Sanchez to improve his conditioning program, pointing to that issue as a possible cause for Sanchez's shoulder issues. Mozeliak said that the time off could afford Sanchez a good opportunity to develop those habits.
"He needs to understand how you utilize that training room," Mozeliak said. "Young players, sometimes it takes a little while for them to do that. And I think this is a great opportunity for him to really take that opportunity to buy into our shoulder program. "
In Sanchez's absence, the Cardinals will likely turn to Jason Motte and Mitchell Boggs as the primary setup men to de facto closer Fernando Salas.
Matthew Leach is a reporter for MLB.com. Read his blog, Obviously, You're Not a Golfer and follow him on Twitter at @MatthewHLeach. This story was not subject to the approval of Major League Baseball or its clubs.