Allen (back) has been downgraded to out for Sunday's Week 2 contest against the Cardinals, Adam Grosbard of The Orange County Register reports.
Allen was originally deemed doubtful on Friday's final injury report, but his status was subsequently downgraded to out. The tight end is dealing with a back injury that kept him out of practice entirely throughout the week. Allen's upcoming absence Sunday will likely move Hunter Long into the Rams' No. 2 tight-end role behind Colby Parkinson.