MF4L: the OL doesn't require seniors, it requires experience, it requires not trotting out guys a year or two years before they should see the field. It's hardly theory to state that OL is one of the most important positions for guys to develop into from an S&C standpoint as well as technique when they make the transition from high school to college football. Let's just use the teams you pointed out as an example, here's where they ranked last year in rushing and the number of starts they had returning as well as this year's projected lines:
UCLA (34th in rushing): '13 75 combined starts, '14 88 combined starts
Baylor (12th in rushing): '13 42 combined starts, '14 64 combined starts
Ole Miss (41st in rushing): '13 82 combined starts, '14 61 combined starts
ND (75th in rushing): '13 78 combined starts, '14 54 combined starts
UNC (78th in rushing): '13 55 combined starts, '14 44 combined starts
Michigan (103rd in rushing): '13 58 combined starts, '14 37 combined starts
Stanford (18th in rushing): '13 82 combined starts, '14 26 combined starts *Replacing 4 starters off the 2013 team
Baylor stands as the outlier in terms of starts to rushing yards, but I would posit that's related to the offensive system, otherwise there's a fairly strong correlation here just using the teams you mentioned between experience on the OL and success rushing the football. Again, I'm not saying a line needs to be all seniors, but it certainly is in a better position to succeed with experienced guys who had time to redshirt and develop within the system before they see the field.
Edit: clicked post somehow, my apologies.
<message edited by scmgoblue on Friday, August 22, 2014 8:42 AM>