Lyles gave up six runs -- four earned -- on five hits over 2.1 innings in a spot start against Pittsburgh on Monday afternoon.
He's not scheduled to pitch as a member of the rotation this weekend, and the ongoing struggles could punch Lyles' ticket back to Triple-A in the near future if the Rockies decide to bring up a fresh arm from Albuquerque in the coming days. Monday's blow-up pushed his season ERA to 8.55 in five starts.