Darvish left Los Angeles' 5-4 win over the Chicago White Sox at Dodger Stadium on Wednesday because of back tightness after pitching six innings.
In three starts for the Dodgers, Darvish is 2-0 with a 2.50 ERA, 1.11 WHIP and 11 strikeouts per nine innings.
Darvish also provided the Dodgers with some insurance for Clayton Kershaw, who was placed on the disabled list on July 24 due to a back injury with no definite timetable for his return.
For all of the things that have gone right for the Dodgers in 2017, injuries to the starting rotation have been a problem. Brandon McCarthy has spent time on the disabled list due to a blister problem. Scott Kazmir hasn't pitched at all due to a hip injury. Alex Wood missed one start in May due to a shoulder injury.
The addition of Darvish, who has 170 strikeouts in 155 innings, was supposed to give Roberts more versatility with his starters.
The Dodgers will coast into the postseason with the best record in MLB and a 19-game lead in the National League West, which gives them the luxury of allowing Darvish to spend some time on the DL, even if his injury isn't significant.