I'll give you mine. It's likely a multitude of factors. If it was as simple as a couple bad position groups, that probably could have been corrected or at least improved on by now.
1. Coaching? Yes, that's probably part of it. I think the transition to the B1G has been much more difficult than the coaches will admit. I think these coaches will grow and learn from this year. I still fully trust Frost as our leader.
2. Lack of developed talent? Oh heck yeah! How many guys have been flying off to the NFL the past 3-4 seasons? Not many, especially on the O and D lines.
3. Sub-par QB play? Definitely, but more ails the offensive performance than just AM's major sophomore slump.
4. Lack of trusted playmakers on offense. When your clear go-to guy is a true freshman (albeit a future star), that's pretty telling.
5. Consistently poor linebacker play. The 3-4 scheme cannot possibly be effective without good linebacker play.
6. Inconsistent special teams. Some bright spots now and then, like a few blocked punts, but overall not very good. Especially the kicking game.
So, in summary, most everything needs to get better for this thing to get right. I think it will happen, but could be another 2-3 years. It's hard as hell, but we have some patience.