Gallen's scheduled start against the Rockies on Thursday was postponed, Bob Nightengale of USA Today reports.
The two teams decided to postpone Thursday's series finale in protest of the recent police shooting of Jacob Blake. While the Diamondbacks have yet to disclose their upcoming rotation plans, Gallen -- who owns a 2.25 ERA through six starts this season -- seems likely to get the ball Friday, which would push the rest of the rotation back a day.