Baker took a step forward with a solid outing against the Red Sox's Triple-A club Saturday morning -- allowing one run on four hits over four innings while throwing 60 pitches -- but he simply has too much catching up to do to be ready for the season.
"His pitches were a little more crisp, but there's still some work to do there, so we're going to DL him," Ryan said. "We'll see what he feels like tomorrow. If all's well and he's OK and he can throw his bullpen [session], then we'll probably throw him out there Thursday."
Baker is expected to start in Class A Fort Myers' first game of the season on Thursday, and he will be eligible to return from the disabled list on April 11. The Twins don't need a fifth starter until April 15 because of an off-day on April 10.
Baker said after his start against Triple-A Pawtucket that he's making progress with his elbow, but he just needs more time to get it fully healed.
"I'm letting it rip, but is my arm 100 percent or in midseason form? No," Baker said. "I'm definitely confident it will get there, but it just might take a little bit of building up the pitch count."
Ryan also indicated that right-hander Jason Marquis isn't likely to be ready to open the season. He's been tending to his 7-year-old daughter who was seriously injured a bicycle accident last week.
Marquis is expected to return to Fort Myers soon, but he is a candidate to start the year on the bereavement list, which means he'd be out for a minimum of three games and a maximum of seven games.
With Marquis not ready to start the year, right-hander Liam Hendriks is scheduled to start the third game of the season against the Orioles on April 8.
"He's put himself in pretty good position," Ryan said before adding Hendriks could stay in the rotation if he fares well. "Once you give that guy the ball, and they keep getting people out, you keep giving him the ball. You see where it takes us. He may throw so good that you don't have to worry about it."
Right-hander Nick Blackburn is slated to start the home opener against the Angels on April 9, which Baker was originally scheduled to start.