The need for another reliever arose when the Cardinals had to put Matt Belisle on the 15-day DL with elbow inflammation.
"He's had a terrific year," manager Mike Matheny said of Hatley. "[He was] a guy who impressed us in Spring Training. We found an opportunity to keep showing him in the spring, and this year he's been doing a nice job pitching late innings in Memphis. He seems to be a guy who can eat up some innings, but get critical outs for us when we need them."
Hatley signed as a Minor League free agent in November and stuck around Major League camp until the Cardinals made their final cuts. He then posted a 1.69 ERA over 27 games (37 1/3 innings) for Triple-A Memphis.
"I always felt like I was a big league pitcher, and it just so happened that this was the right fit for me, the right organization," Hatley said. "I couldn't be more excited for the opportunity."
• Aside from announcing that John Lackey will start the series finale against the White Sox, Matheny said he will refrain from announcing any additional rotation plans until Wednesday. Lefty Jaime Garcia remains the wild card in those plans, though it's looking increasingly unlikely that he'll be ready to start on Thursday.
Garcia, who exited his start last week due to cramping around his left groin, has continued to delay his bullpen session due to continued discomfort. He did not throw off the mound Tuesday, but did play flat-ground catch.
If the Cardinals can't start Garcia on Thursday, they could either move Michael Wacha up a day to pitch on regular rest or summon lefty Tim Cooney from Triple-A to make the spot start. Cooney was pulled from his outing with Memphis on Sunday so that he could be ready, if needed.
• Matt Holliday (right groin strain) took batting practice again on Tuesday but did not test his injury running. Holliday is expected to add running into his rehab work sometime this week.
• With the White Sox starting lefty Chris Sale, Matheny used Tuesday as an opportunity to rest left-handed hitters Kolten Wong and Matt Carpenter.
• Cardinals broadcaster Tim McCarver will share the booth with Bob Costas on Thursday as MLB Network televises the Cardinals' series opener against the Padres. It will mark the first time the two legendary broadcasters have called a game together since 1980, when they joined up for "Game of the Week" broadcasts on NBC.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, follow her on Twitter @LangoschMLB and like her Facebook page Jenifer Langosch for Cardinals.com. This story was not subject to the approval of Major League Baseball or its clubs.