This is no different than Wimbush versus Book and Wimbush didn't actually lose in the first 3 games but couldn't make the offense move well enough to beat good teams later.
Pyne obviously is far from a Heisman contender or national championship caliber QB but his strengths and abilities make the offense move better than Buchner.
Injury or no injury, Pyne is the better option to make the offense go.