The 28-year-old, who went on the disabled list on Aug. 13 with a mild inflammation in his right elbow, is close to being recovered, according to MLB.com's T.R. Sullivan, but he has not begun a throwing program.
"It's kind of one of those deals — if we wanted to be aggressive and push it, we could get him back the last week," said general manager Jon Daniels. "But we don't see any value in that. There is a lot more risk to it."
The Rangers enter their game against the Mariners on Saturday with the worst record in baseball at 53-88, and they've lost seven in a row.
"I have to go by what the doctors and the trainers say, so it is what it is," Darvish said. "Since I haven't picked up a ball I can't really tell, but I think it's getting much better.
"My job is to throw throughout the season, so I'm disappointed I wasn't able to complete my job."
Darvish was 10-7 with a 3.06 ERA in 22 starts this season, his third with the Rangers. The three-time All-Star is 39-25 with a 3.27 ERA in 83 career starts.
- Chris Mascaro