The Steelers have a different problem. Metcalf is one of the best receivers in the NFL, and the Chargers had one safety always drifting to Metcalf's side the entire game. Couple that with aged Rodgers not being able to deal with (e.g., elude) the extra pressure last night, and a few drops by the other receivers and you have problems. Rodgers also missed quite a few throws last night.
But, we don't have anyone close to Metcalf's level on our squad. And, let's be realistic here, Coleman would be nothing more than a backup on the Steelers.