Determining the best backup quarterback ever is really complicated. Steve Young and Aaron Rodgers backed up Joe Montana and Brett Favre, respectively, but neither Young nor Rodgers morally feel like they belong in the discussion of best backup quarterbacks.

There are a couple of ways to measure how a backup quarterback fares. One way is on a game-by-game approach: i.e., the starter gets injured or pulled, and now the backup is in charge. That’s the sort of thing Frank Reich, at least anecdotally, excelled at. ^[1]Post for another day (or another author): Which quarterbacks were the best off the bench? The more interesting, and easier question to analyze, is to take a season-by-season approach. If a quarterback does not start his team’s season opener, he’s a backup. If he does, he’s not.

Using that concept, the name that immediately jumps to mind is Earl Morrall.  After all, he led two teams to Super Bowls during seasons that began with him on the bench. But what do the numbers say?

Ironically, my proposed definition excludes what is undoubtedly the greatest season in backup quarterback history: Kurt Warner in 1999. That season may have been a top-three season in quarterback history, but it began with Warner second on the depth chart to Trent Green. When Rodney Harrison ended Green’s season in the preseason, Warner become the starter, which would exclude his ’99 season from this analysis.

And, uh, ironically again, Morrall’s best season is excluded, too.  His top year was in 1968 when he won the NFL MVP, but since Johnny Unitas was injured in the preseason, Morrall isn’t labeled a backup by this formula, either. But I do think that the Warner and Morrall examples are rare enough that we can proceed with minimal concern. [continue reading…]