Everyone loves the backup quarterback.
He has all the promise of an all-pro player without ever actually having to demonstrate it on the field. It is the blessing and curse of being second string.
Even if he is thrust into a game and performs poorly, fans will simply say "he played pretty well, for a backup". When it comes to the second man under center, fans are understanding, forgiving and adoring, almost to a fault.
As soon as the starter begins to falter, legions of fans romanticize the on-field prowess of the quarterback in waiting.
The list of backups-turned-starters is endless, and includes the likes of Tom Brady and Steve Young, so the aim was to focus on those that spent the majority of their careers holding the clipboard or in backup/starter limbo.