For me, PPG mean very little, there could be a multitude of reasons why they didn't run the score up. YPA, that tells me if the passing offense was successful or working. San Francisco's YPA under Roman were: 16th, 2nd, 7th, 23rd. Buffalo's the last four years: 21st, 24th, 28th, 28th
I'd say San Fran was below average this year but was still better than Buffalo's. He also had some very very good years.