Manager Robin Ventura indicated after Saturday's loss to the Twins that Shields tweaked his back during the start, Daryl Van Schouwen of the Chicago Sun-Times reports.

EDGE Analysis

Back injury or not, Shields was again a disaster during his time on the mound, giving up five runs on five hits (including three homers and a double) and four walks over 2.1 innings. He's now totaled a 6.07 ERA and 1.64 WHIP over 151.1 frames on the season, making him one of the majors' least productive starters. Ventura doesn't believe the back issue will plague Shields going forward, but the White Sox may need to seriously evaluate the former ace's spot in the rotation.