Some of it is scheme. The rest of it is injury and lack of talent being exposed. Offensive lines get studied by opponents just as any other position. Over the years we've done a lot of patch work strategies to cover up the lack of talent, but those tactics are starting to dry out.

Evans is a real talent, but is not fully healthy. After him, there is not a single starter on that line who is really a legitimate NFL lineman. Armstead fits this scheme with his agility, but (apparently) he isn't ready technique-wise.