Well he was criticizing the players, because that room doesn't have enough talent. Pretty much a standard opinion by everybody. Changing the strength coach won't solve that, and neither will changing the OC. They need personnel upgrades. Only difference is people would probably prefer EDC not say that publicly, but I don't care about that.
Roman wouldn't be the lowest ranked OC. We pretty much know Olineman, RBs and TEs love him, so I doubt they'd be saying he's terrible. WRs will hate him, of course.
There's plenty of other really bad OC's out there. Greg Roman would look like Bill Walsh compared to whoever the OC was in New England last year.