How would one ever make a judgement on that? Whitmer had a gift for a making a mistake at the worst possible time. There is no statistic that can quantify number of game crushing errors he committed.
On the other hand, Boyle looked just hapless in his chances to lead the team.
Either way we lose.
If you want to compare physical attributes, Boyle beats Whitmer in just about every category. Better size, moved better, stronger arm, better release, etc. So was Boyle a better prospect, absolutely. Was he a more productive player, not in any meaningful way.
I do stand by my insistence (later executed by Diaco) that Whitmer had to be pulled out of the starter slot.