Ohio, in your opinion has Adkins done an abysmal job because....He's not looked at his linemen...He's choosing to make his linemen fit in his scheme irregardless of whether they're capable of executing it. As opposed to designing blocking a scheme that promotes the strengths of his linemen.
Or is it simply he's a bad position coach because he can't judge talent, position efficientcy, read defenses, glean from defensive film, or even a tough conditioner?
Coaching offensive line is both the easiest and most difficult position. It's the easiest because there's a lot that simply doesn't need to be focused on and the hardest because it requires an almost neurotic attention to detail. For me, I've always been the type to wear out defensive film in an attempt to see what is going on in the minds of the defensive linemen (usually, it's a dead hamster on a wheel). I have no real interest in watching the overall play of the defense or establishing tendencies unless I'm surrounded by idiots who run the offense. But for the most part, "missing the forest for the trees" is a big part of what goes into good line coaching.
As for "his scheme", there's only one scheme that matters: the offensive coordinator's. Usually it should go like this.
OL COACH: Will we be doing man or zone blocking?
OC: (whatever the answer may be)
OL COACH: Okay, thanks.
Obviously that's oversimplifying it, but not to a great extent. 95% of offensive coordinators aren't going to say, "Here is the play, now you determine the blocking scheme." And if they do, Adkins is hardly the type that I would want doing any sort of planning. That said, an OL coach is well within his rights to say, "On xx play, I think we can make xx adjustment this week because of....". But for that, he had damn well better have an awful lot of practical knowledge to back that up.
To your last query, in order....
1) I don't know if he can judge talent
2) I don't know if he can position effectively or efficiently
3) I don't know if he can read defenses, but for the most part that's not his job
4) I don't know if he can glean from defensive film
5) I don't know anything about his conditioning practices, but from the overall whole of what I've seen of him, I can imagine him being the type who would make his guys go out there and do what they did in the 1940s because "that's how it's always been done".
Line play is built on two things: get there quickly and in a bad mood. I tell my guys from day one....I can live with you blocking the wrong guy. But if you block the wrong guy, he'd better not be in a position to make a play after you hit him and you'd better be looking for the next guy to hit.
My beef with Adkins is that his guys play like garbage. They don't fire off quickly, and if they do it's negated anyway by grabbing the DL under the armpits and trying to steer him away from where the RB is going. If you want to see how much sense that makes, kneel in front of your TV and put one hand on each side. Now push backwards. Illogical, isn't it? Now put both hands in the middle of the screen and push backwards. That's the Adkins difference.