Let's put the facts on the table:
Here's the comparison of running backs and fullbacks who were drafted and played in at least one NFL game by year of draft:
2000 to date:
OSU: 4 (Pittman, J Martin, Wells, Wiley)
MIA: 5 (Gore, McGahee, Davenport, Portis, J Jackson)
1995-1999
OSU: 3 (Montgomery, Sualua, E George)
MIA: 4 (E James, N Luchey, Derrick Harris, J Stewart)
1990-1994
OSU: 5 (R Harris, Cothran, By'not'e, R Smith, S Graham)
MIA: 1 (Donnell Bennett)
1985-1989
OSU: 4 (Workman, Jamie Holland, Byars, Spencer)
MIA: 6 (C Gary, Bratton, W Williams, Highsmith, Darryl Oliver, Bentley)
That's the list--no fuzzy stuff on the potential of current college backs, etc. Note that I'm not trying to compare them on a pure count of backs drafted who played. Some of these backs on either side just had a cup of coffee in the NFL. I'm just trying to provide facts here, since most of us on this board don't have this list in front of them.
Here's my take: a couple of good backs on each side, with probably a couple more on the MIA side lately than the OSU side. Before the mid-90's, the list is definitely more skewed towards OSU.
But, rather than compare talent, here's the underlying point: if you are a good college RB, you will get the NFL's attention at either school.
Lately, Ohio State may have had less talented RB's than Miami, or maybe OSU hasn't developed their RB's as well. There's no way to prove that argument either way. But Ohio State's RBs that have rushed for some success in college (Wells, Clarett, Pittman) have all been drafted and have had the opportunity to make it in the NFL. So have Miami's.
What any RB does after being drafted is a function of talent, attitude, and opportunity (i.e. Ryan Grant of the Packers this year, Terrell Davis in his rookie year), most of which is not controlled by a player's alma mater.