Strength & conditioning under Bo was actually pretty good. I'm choosing the words "pretty good" carefully - so, not "great" but also not "bad."
Then Riley not only didn't bring in quality linemen on both sides of the ball but practically abandoned serious weight training, at least as far as I understand it.
Outside of Ohio State's insane evolution to a completely other level, the rest of the decent-good teams (outside of Indiana) still play power football on both sides of the ball. In our division, Wisconsin & Iowa consistently develop strong offensive linemen, defensive linemen, and linebackers.
Until we get our big guys strong again - really big & strong - we will continue to suck in the B1G. This is foundational, and it doesn't get fixed in just two seasons.