Like it or not, the NFL pre-draft season is in large part propelled by numbers-driven events, such as the combine and the various college pro days held across the nation, that can sometimes indicate the skill level of select players at certain positions, including wide receiver and cornerback among others.
But the offensive line is almost its own species in that numbers seldom tell the tale about the great big body guards entrusted with arguably the most important task on the field—protecting the quarterback.
Any one single tackle, guard or center is often only as good as the players around him.