Ryan was 1-1 with a 6.53 ERA in 25 games with the Toronto Blue Jays before he was released on July 8. The Jays owe the left-hander $15 million, and the Cubs will be obligated to pay him a prorated share of the Major League minimum if he makes the team.
Ryan will report to the Cubs' Minor League facility in Mesa, Ariz., on Sunday and work with pitching coordinator Mark Riggins. When he's ready, he will join Triple-A Iowa, but there's no timetable.
"He's not ready [now]," assistant general manager Randy Bush said. "What's great is that he wants to do it the right way. He wants to go to Mesa, get work on his delivery. He wants to get himself back to feeling good about where he's at and how he's delivering the ball. When he's ready to go and feels sharp, that's when he wants to go to Iowa."
The Cubs have one lefty in the bullpen, in Sean Marshall, and no one available. Neal Cotts was on the Opening Day roster but underwent Tommy John ligament-replacement surgery on his left elbow.
"We feel there's a whole lot of upside for us," Bush said. "It should be a thing that can work well for both sides. He can go about getting himself ready at the right pace."
Ryan told the Cubs that he felt inconsistent work had contributed to his struggles this season. In 2004, Ryan struck out 122 in 87 innings for Baltimore.
"If he pitches anywhere near how he pitched with the Orioles and Toronto, he'll help us," manager Lou Piniella said. "But I think that's down the road just a little bit."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.