Eli Manning played like an elite quarterback while leading the New York Giants to a championship last year, but he has struggled often this season.
As the most scrutinized position in sports, the NFL quarterback has his every move analyzed under the microscope.
In many instances, this highlights inconsistencies among several top passers who are a few unheralded mistakes away from reaching superstar status.
After a year removed from the game, Peyton Manning has returned as the same steady force. His 204 passing yards last week, which resulted from the Denver Broncos running early and often, represented a season low.
Reigning MVP Aaron Rodgers has not thrown more than one interception in a game since the 2010 NFC Championship.
These guys are as reliable as they come. But below the premium class rests a group of quarterbacks who play brilliantly at times but poorly on many other occasions.
Eli Manning leads this class of up-and-down signal-callers. He outplayed Rodgers and Brady en route to his second Super Bowl ring last winter, but he's still prone to eye-gouging mistakes that leave New Yorkers wondering if they're watching Mark Sanchez.
These five quarterbacks frustrate NFL fans with unrealized upside stunted by stints of mediocrity.
Rivers' 94.2 quarterback rating and 63.7 completion percentage are both the highest marks among the three. He accumulated over 4,000 passing yards in each of the past four seasons, a streak that will snap this year barring two monster games to conclude 2012.
But lately, Rivers can't maintain control of possession. In 30 games over the past two seasons, Rivers has turned the ball over 47 times.
An apparent dip in arm velocity is often cited as a reason for his decline over the last two seasons, and the loss of Vincent Jackson has robbed the offense of its big-play threat.
Still, how much longer can Rivers lounge around as the best quarterback on a subpar team? Quarterbacks occasionally receive too much credit for a team's success (see Sanchez), but teams with passers of Rivers' stature rarely miss the postseason three straight times.
Rivers has showed signs of life, scoring three touchdowns during three separate games, but he also yielded four interceptions and a fumble during a monumental collapse against the Broncos that signified the beginning of the end of the San Diego Chargers' season.
With a surplus of talent in a division that was often shaky before Peyton Manning's arrival, the Chargers wasted every opportunity to capitalize. Norv Turner is a huge part of the problem, but eventually one has to wonder whether Rivers also plays a big part in San Diego's inability to get out of its own way.
Jay Cutler never lived up to the potential he exhibited throughout 2008. Since everyone expected better, Cutler has become a whipping boy among pundits who bash him for bullying teammates or having the audacity to not play through a significant injury.
There are games where Cutler puts it all together, and then he's special to watch. Against a strong Dallas Cowboys defense, he completed 18 of 24 passes for 275 yards and two touchdowns. He helped the Chicago Bears torch the Tennessee Titans to the tune of 51 points, but anyone besides Sanchez can beat the Titans (sorry, it's too easy).
In two pivotal games against the Green Bay Packers, however, Cutler completed 47.9 percent of his throws for 261 yards, two touchdowns and five turnovers. The seventh-year quarterback has done little to prevent Chicago from spiraling out of control, from 7-1 to out of a playoff spot.
In his defense, Cutler has to deal with a lackluster offensive line and a receiving unit that relies entirely on Brandon Marshall. In better circumstances, Cutler could probably pile on more passing yards.
And for whatever it's worth, Cutler is at least consistently inconsistent. None of his years with the Bears stand out as noticeably good or bad. He annually completes around 60 percent of his passes with a yards-per-game average in the low 200s.
Poor Tony Romo. At this point, his family probably criticizes him for brushing his teeth inefficiently and washing dishes at a mediocre level.
Truth be told, Romo is good. Really, really good.
During his career, Romo has completed 64.9 percent of his passes, higher than Brady's rate. When he stays healthy for 16 games, he routinely surpasses the 4,000-yard plateau. His 95.7 career quarterback rating is a few percentage points higher than Peyton Manning's.
And yet, Romo frequently becomes a punchline after throwing a gut-wrenching interception at the most inopportune time.
While Romo fails to receive the credit he deserves as an exemplary quarterback, he also partly has himself to blame.
Contrary to popular belief, interceptions are usually not a huge problem for Romo in comparison to most quarterbacks, but during a few games this year he's given them away like gifts at an Oprah holiday special.
In Week 8, he threw four interceptions against the Giants in a game that the Cowboys still almost won. Like he often does, Romo rallied the team after putting them into a hole, but they fell inches short of finishing the comeback win.
Earlier that month, Romo distributed five picks in a loss to Chicago. For someone who looks every bit the part of a top-10, even top-five quarterback at times, he finds a way to make it all for naught.
Remember when Joe Flacco declared himself a top quarterback before the season started?
Even worse, remember when experts actually hopped on board with that claim after he opened the year on a positive note?
When Flacco completed 21 of 29 passes for 299 yards and two touchdowns to begin the 2012 season, that dirty "E" word popped up more and more. His 382-yard, three-touchdown outing led the Baltimore Ravens to a colossal Week 3 victory over the New England Patriots, and he followed that up with 356 yards the following week.
Since then, he nearly squandered a game against the Kansas City Chiefs, completed less than half his passes and tossed two picks in an embarrassing loss to the Houston Texans, and he lost a pivotal division game to Charlie Batch and the Steelers.
The 27-year-old has eclipsed a 115.0 quarterback rating four times this season, but faltered below a 70.0 rating in four instances.
Pundits are constantly waiting for Flacco to take the next step as a Pro Bowl-quality quarterback. If they keep holding their breath in anticipation, they'll eventually turn as purple as Baltimore's color scheme.
Flacco's not a bad quarterback. There's nothing wrong with a passer who's completed 60.4 percent of his passes over the course of his career alongside a 86.0 quarterback rating.
He's a solid, above-average quarterback, but the glaring imperfections mixed in with glimpses of stardom drive everyone crazy.
On one hand, Eli Manning has bested Brady twice on football's grandest stage. He sits on a prestigious list with Brady and Roethlisberger as the only active quarterbacks with multiple Super Bowl rings.
During those two playoff runs, Manning threw for 2,073 passing yards with 15 touchdowns and just two interceptions.
Man, if only that guy could show up every week.
Once the Giants won their second championship under Manning's rule, he quickly earned that "elite" label from the same fans and analysts who previously thought it looked hilarious when presented in the same paragraph as his name.
A few times this season, Manning reminded Giants fans how extraordinarily lucky they are to have him orchestrating their offense. During other games, it was hard for fans not to scratch their heads and wonder if this is really the same guy whose rousing playoff performance just a year ago led many to wonder if he's as good as his brother, one of the sport's greatest players ever.
In their Week 2 game against the Tampa Bay Buccaneers, we got a taste of both sides. After burying the Giants in a hole with three interceptions, he dug them back out with a career-high 510 passing yards.
This is nothing new for Manning and the Giants, the most inconsistent quarterback and team in football, respectively. On a good day, they look unstoppable. On a bad day, they're as laughable as Sanchez's butt-fumble.
One such day occurred last week at Atlanta, where Manning threw for 161 yards and surrendered two interceptions in a shutout. In a horrific stretch from Weeks 7-10, he tossed one touchdown and six picks.
Then he returned from a bye week to decimate the Packers.
His unstable play keeps him out of the top tier occupied by Brady, Rodgers, Peyton and Brees, but his constant late-game and postseason heroics secure his status as a quarterback you want leading your offense to overcome a deficit with two minutes left.