NFL history is littered with QB2s waiting for their shot. Most of them, like the 49ers' starter, thought they too were better than the guy atop the depth chart.
Only a handful of them got a chance to prove it. Fewer still could actually claim that they deserved first-string consideration in the first place. And unseating a legend? You can count those guys on one hand, Jimmy G.
That's not to say it's impossible, though. Check out the seven best Hall of Famer backups to ever ascend to a starting QB role.
7. Marc Bulger
Draft year: 2000
Accolades: 2x Pro Bowler
"The Greatest Show on Turf" looked about ready to pack it up in 2003. That's when Bulger took over for an injured Kurt Warner and guided the Rams back from an 0-5 start. His passer rating? A very impressive 101.5, enough to end Warner's wonderful run in St. Louis the next year.
6. Frank Reich
Draft year: 1985
Accolades: Led the biggest comeback in NFL history
So what if the Colts' current head coach didn't start a game in the 1992 regular season? Reich subbed in for Jim Kelly in the '92 Wild Card and engineered a 32-point comeback. That's enough to warrant a spot on this list.
5. Craig Morton
Draft year: 1965
Morton started out as Don Meredith's backup. Then, depending on Tom Landry's mood, he either was the Cowboys' QB1 or Roger Staubach's backup. Despite a nasty Super Bowl V interception, Morton was integral to the 1970 Cowboys' season. Years later, he became the first QB ever to lead two different teams to the Super Bowl (Cowboys, Broncos).
4. Tobin Rote
Draft year: 1950
Accolades: 1957 NFL Champion, 2x Pro Bowler
Do yourself a favor and look up Tobin Rote. He led the league in touchdown passes in 1955 and 1956 -- only to be replaced by Bart Starr in Green Bay. Rote was traded to Detroit in 1957, where he backed up another Hall of Famer in Bobby Layne. In the 1957 Western Division Championship game, Rote was thrown into duty for Layne and led the Lions to a comeback win with three touchdown drives in five minutes. Not bad for a QB2.
3. Earl Morrall
Draft year: 1956
Accolades: 1968 NFL MVP, 3x Super Bowl Champion, 1968 NFL Champion, 2x First-Team All-Pro, 2x Pro Bowler
Earl Edwin Morrall is arguably the greatest backup QB of all time. Despite having a Pro Bowl year as the 49ers starting QB in 1957, Morrall was traded to the Lions in 1958 and would go onto play for six teams in his 21-year career. During his stints he became an understudy for four Hall of Famers -- Y.A. Tittle, Len Dawson, Fran Tarkenton, and Johnny Unitas. In 1964, after Unitas suffered an arm injury, 34-year-old Morrall became starting QB of the Colts and won league MVP. He stepped in again for an injured Unitas in Super Bowl V, and again in 1972 when the undefeated Miami Dolphins needed an emergency starter for the injured Bob Griese.
One more awesome footnote: Morrall served as the QBs coach at Miami, where he tutored Jim Kelly, Bernie Kosar, and Vinny Testaverde. Pretty cool, Earl.
2. Aaron Rodgers
Draft year: 2005
Just picturing Rodgers holding a clipboard now seems ridiculous. But that's exactly what No. 12 did from 2005 to 2008, when he sat behind Brett Favre. In 2008, Rodgers became the full time starter and ascended into the Hall Mary-throwing, Discount Double Checking force he is today.
1. Steve Young
Draft year: 1984
Few teams ease away from their franchise's best all-time quarterback gracefully. Only one (so far) has done it in style; after four years behind Joe Montana, the Niners swapped him with another future Hall of Famer in Steve Young in 1992. The end result? A record-breaking Super Bowl XXIX victory and two regular season MVP awards for Young.