Simmons is listed as questionable for Sunday's game versus the Pistons due to lower back injury management, Erik Slater of ClutchPoints.com reports.
Simmons sat out the first leg of a back-to-back earlier this season, so it wouldn't be surprising for him to miss Sunday's contest. If Simmons is ultimately ruled out against Detroit, Nic Claxton and Noah Clowney would be candidates to receive increased playing time.