Gragg, who had exited Thursday's preseason finale against the Eagles with what was labeled as a knee injury, is believed to have suffered a broken ankle, Rich Cimini of ESPN.com reports.
This is an unfortunate development for Gragg, who's likely looking at an extended absence. He looks to be a strong candidate to be cut over the weekend, though he could revert to the Jets' injured reserve list if he clears waivers.