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.

Nick Foles had a backup season for the ages in 2013, although it’s too early in his career to see if he’ll fall within the definition of “backup quarterback.” Most of the best seasons by a backup came from the hands of longtime starting quarterbacks: Randall Cunningham in 1998 with the Vikings, Vinny Testaverde in 1998 with the Jets, Chad Pennington in 2002 with the Jets, Boomer Esiason with the ’85 Bengals, Craig Morton for the ’70 Cowboys when Roger Staubach was the starter, and then Staubach in ’71 when Morton was the starter (remember, this was during the brief era when Tom Landry was a little crazy).

Morton in particular presents some issues. In 1969 and 1970 he was excellent, but he gets labeled a backup because Staubach started week 1 in both seasons. I tend to think of him as a starter (or co-starter with Staubach), but if you don’t, those two seasons are enough to put him in the running for title of Best Backup Ever. Morton was also solid off the bench in 19 starts for Denver in ’79 and ’80, and very good as a starter in ’77, ’78, and ’81.

So how did I go about running a query to determine the best backup ever?

• 1) Record the week one starter in every season since 1960. The only manual override was in 1968, when I made Unitas the starter. This is stacking the deck for Morrall, I realize.
• 2) Calculate the league average Adjusted Net Yards per Attempt for each season.
• 3) Give each quarterback credit in each season using the following formula: (ANY/A – 0.75*League_Avg_ANY/A) * (Pass Attempts + Sacks). This is essentially giving quarterbacks credit for their value over replacement.
• 4) To compile career grades, only give quarterbacks credit for their performances in seasons in which they were not the week one starter. Call this the Rich Gannon adjustment.
• 5) To qualify, a quarterback must not have been the week one starter in at least half of his seasons. This is the Kurt Warner/Ben Roethlisberger adjustment. ^[2]Roethlisberger began the 2004, 2006, and 2010 seasons on the bench, but wound up having magnificent years in ’04 and ’10, in particular.

By this method, Morrall does in fact come out as the top backup ever.  Here’s how to read the table below: Morrall first played in 1956 and last in 1976, and played in 17 seasons since 1960 (that’s the first year we have data on quarterback starts).  In only four of those seasons did he begin the season as the starter, which leaves 13 seasons since 1960 where he began as the backup.  That means he began the season as the starter just 23.5% of the time.  For his career, he produced 4,930 yards of value over replacement but that includes all 17 seasons.  As a backup, he produced 3,903 yards of value over replacement, and that’s the most ever (the “Backup Val” is the metric by which the table is sorted).  Finally, he had 1,458 dropbacks in seasons as a backup.  As always, the table below is fully searchable and sortable, and it displays the top 50 backup quarterbacks since 1960 by this method. ^[3]Note: I removed Nick Foles and Colin Kaepernick from the table, who would otherwise make it, but I’m not in a trolling mood today.

• By this method, Morrall does come out on top, which seems appropriate. The deck was stacked a bit by including his 1968 season, but one could argue that Morton’s 1970 season shouldn’t really be included because it’s a Backup In Name Only type of year. Morton also spent more time as a starter than Morrall, so depending on how you want to define a backup, he arguably wouldn’t qualify.

• After those two comes Doug Flutie, who definitely belongs in the discussion. Of course, Flutie is most famous for breaking Neil’s age-adjusted quarterback rating system. Okay, maybe that’s not what he’s most famous for, but now that’s the first thing I think of when I see his name. Curses, Neil!

• Speaking of quarterback name association, I don’t think I speak out of turn when I say that people see “Gus Frerotte” and think “concrete headbutt!” But that’s a shame: Frerotte was a pretty good quarterback, and one of the best backups ever. He made the Pro Bowl in 1996, but that season doesn’t get included since he started 16 games. No, Frerotte makes it to #4 on the basis of four good seasons as a backup with four different teams.
  • In 1995, Heath Shuler was still the starter in D.C., but Frerotte wound up starting 11 games and posted a league average ANY/A.  He led the NFL in yards per completion (Norv!), with a 34-year-old Henry Ellard as his top target.  Ellard, of course, was a Turner favorite.
  • In 1999, Frerotte was in Detroit, and Charlie Batch was the starter to begin the year.  Frerotte started six games but was above-average in ANY/A  on 316 dropbacks. The bad news? Frerotte went a combined 5-12 as a starter in ’96 and ’99.
  • In 2000, Frerotte was in Denver backing up Brian Griese. This was the weird year where Griese led the league in passer rating but was limited to ten starts.  Frerotte went 4-2 as a starter and posted well-above average ANY/A numbers, although they were still inferior to Griese’s.
  • In 2003, Frerotte started just two games in lieu of Daunte Culpepper. But what he did in those games! Frerotte went 16/21 with 267 yards and 4 touchdowns in a win over the 49ers in week 4, and 14/24 for 239 yards with 2 touchdowns in a 39-26 victory in Atlanta the following week.  He replaced Culpepper in a game against Detroit in week 3, and threw the game-clinching touchdown that week, a 72-yard pass to Kelly Campbell.

• Don Strock doesn’t rate all that highly here, but he had some great performances in limited samples. In 1983, he went 2-0 and posted the highest ANY/A of any quarterback in the league with a minimum of 50 passes. In 1979, he went 3-1, and ranked 2nd to only Staubach in ANY/A (min: 50 att). At age 38, he even came out of retirement to lead the Cleveland Browns to the playoffs, and posted solid numbers then, too. Stock’s most famous game was when he came off the bench in the Epic in Miami and threw for over 400 yards and four touchdowns.

• Only one quarterback produced over 1,000 yards of value above replacement in two seasons in which he began as a backup: Kurt Warner in 1999 and 2007.

• Another quarterback who had some strong backup performances for multiple teams was Mike Tomczak. In 1988, he added 474 yards of value over replacement for the Bears when Jim McMahon was injured. Four years later in Cleveland, Bernie Kosar began the season as the starter but Tomczak was the much better passes. And four years after that, in Pittsburgh, he stole the job from Jim Miller. 

What quarterbacks stand out to you? How would you go about defining the best backup quarterback ever?